Definite Compounds Research Articles

Fire hazards of calcium hypochlorite

“Calcium hypochlorite, 70% available chlorine” is a commercial chemical which is transported in large quantities generally packed in steel drums. It is classified by the I.M.C.O. Code as an Oxidising Agent. During the past five years there have been about a dozen serious accidents in ships involving this material. The losses caused have been very large, amounting to many millions of pounds sterling. A number of the P. and I. Clubs in London set up a sub-committee to investigate the hazards associated with the substance. The investigations include a research programme carried out at the Royal Armament Research and Development Establishment, Woolwich, England. It has been found that ignition may occur in some circumstances spontaneously, by mechanical stressing or by admixture with some combustible substances. The commercial material is not a definite chemical compound but a mixture, the nature and properties of which may vary according to the nature of the raw materials and method of manufacture. Accidental ignition may be followed by explosive effects and the fire evolves large quantities of oxygen, which produce an almost uncontrollable burning of any combustible material nearby. It is apparent that the hazards are far more serious than those ordinarily associated with other oxidising agents.

Hémoglobine fœtale et hémopathies acquises

Though the human γ chain of haemoglobin has appeared initially to be a definite chemical compound, Schroeder et al. showed that at least two and possibly four γ chain loci are active in human newborn. These genes control the synthesis of two different types of γ chains, the G γ and the A γ chains, which differ at least in the position 136 where glycine is replaced by alanine. So, there are two different fœtal haemoglobins which are not separable by chromatography or electrophoresis. Their levels are obtained from the ratio of glycine and alanine at the 136th residue which is included in the third and last peptide obtained by bromide cyanogen (BrCN) hydrolysis of the γ chain : the γCB3 peptide. Schroeder et al. studied the variations of the level of these two chains during the normal ontogenic development and in several cases of hereditary persistance of fœtal haemoglobin (HPFH) and β thalassemias. In this work we studied the γ chains synthetized in different types of anemia, apparently acquired with elevated level of fœtal haemoglobin, where the haemoglobin F level was included between 1 and 15 p. cent, such as refractory anaemias with excess of myeloblasts (RAEM), acquired sideroblastic idiopathic anaemias (ASIA), idiopathic aplastic anaemias, and some varieties of leukemias, especially juvenile myeloid leukemias (JML). We used the method described by Schroeder with slight modifications since our samples were relatively poor in F haemoglobin. After chromatography on Amberlite Biorex 70, the A IC haemoglobin F haemoglobin mixture was fractionated by starch maize block electrophoresis, which is a very efficient method to separate a F/A IC mixture. Then, we used Biogel P10 instead of P100 for the separation of the BrCN peptides, since it seemed to us more appropriate for isolation of the thirteen amino-acids γ CB3 peptide. With this technic, we examined the γ chains of two normal cord blood, of two very young embryos blood and of eleven patients. All of them where presumed to have an acquired high level of fœtal haemoglobin except one case, which was known as an HPFH case and shows the 0.4, 0.6 level of G γ chain described by Schroeder in one category of negro cases. The level of G γ and A γ chains of the cord blood tested are identical to the results found by Schroeder. The G γ /A γ ratio of the embryos are identical to those of the full term fœtuses. Since the embryos were respectively twelve and sixteen weeks old it would prove that the A γ gene is not repressed in the very early time of the fœtal development. The majority of the studied pathological cases (7 out of 10) showed a G γ /A γ ratio very close to 0.80 which is a ratio of the « fœtaltype. The other cases had a ratio between 0.50 and 0.65 which is a ratio observed in the normal adults. Among the « fœtaltype cases, one case must be extracted because the high level of its fœtal haemoglobin is probably not due to its PK deficiency, but seems to be due to an unobserved type of caucasian HPFH. The Kleihauer technic showed in all our cases an heterogeneously distributed F haemoglobin except in the HPFH cases, and no difference was noted between the different other cases. The proportion of G γ and A γ chains in our patients seems to be uncorrelated with the nature of the disease, the level of the haemoglobin synthesized, the state of the bone marrow or the nature of the treatment. There is perhaps some correlation between the level of the total haemoglobin and the nature of the γ chain synthesized, since in the cases with an « adulttype, the anaemia was very recent, at the time of the blood sampling and due to an acute haemolytic crisis. These results clearly show that like in β thalassemias and HPFH, the nature of the γ chain synthesized in the acquired diseases is varying according to the cases. The synthesis of high level A γ chain in some cases of acquired high level of F haemoglobin indicates that the fœtal/adult switch-over of haemoglobin synthesis is more complicated that it has been described until now. It will be interesting to follow the level of the different γ chains according to the genetic or non genetic level of this mechanism.

Thermal EMF of CuO and its dependence on the oxygen partial pressure

1. The\(\alpha (1/p_{O_2 } )\) dependence for CuO is clearly defined over a broad range of oxygen pressures, 1–760 torr. 2. Above ∼390 °C the constant CuO composition characteristic of the hardened state disappears, and there may be a transition from the effects corresponding to a definite chemical compound (e.g., CuO in the hardened state) to effects typical of a metastable saturated solution of oxygen in the metal (Cu). 3. The α(1/T) dependence predicted by the theory is masked under certain thermodynamic conditions by the temperature dependence of the composition of the substance (CuO), and considerable care must be used in evaluating the thermoelectric effects in oxides of varying composition such as CuO. 4. The change in the α sign for CuO occurs in different manners for different temperature ranges on the Cu-O2 state diagram under certain thermodynamic conditions.

The structure of the d-glucose adduct of 3-amino-1,2,4-triazole: Infrared absorption studies

Chemical tests and infrared absorption spectra indicate that the d-glucose adduct of 3-amino-1,2,4-triazole is a definite chemical compound, an amine glucoside or secondary amine. The participation of this amine glucoside in phosphorylating reactions is discussed with respect to the observed effects on carbohydrate-metabolizing enzymes such as hexokinase and phosphorylase.

The Intake of Silica by the Rice Plant with Reference to Blast Disease

The blast disease caused by the fungus Piricularia Oryzae is the most serious disease of the rice crop, but is prevalent only on certain strains of paddy while others are immune to it. Hence the effective control of the disease at present is only through the use of resistant strains. Among the Madras strains, Co, (Coimbatore 4) is highly resistant even under worst conditions while the variety Adt, (Aduthurai 10) is highly susceptiable to the disease. The latter strain is however a high yielder and hence very popular in the Tanjore Delta. In modern times with the advancement of science many of the characters such as resistance and other factors which are indissoluble Mendelian factors of inheritance, located in the genes of chromosomes have been explained through enzymology in terms of certain set chemical reactions resulting in definite chemical compounds. Hence this inheritance of resistance to blast, located in specific strains were aimed to be studied in terms of possible chemical constituents in the strains which bestowed on the strains the disease resistance.

Some consideration of the interaction of the metal peptidases with their substrates.

It is generally agreed that enzymes must form definite chemical compounds with their substrates. This thesis, first clearly stated by Michaelis and Menten (1913), has been tested by kinetic studies on a large number of enzymes. Direct physical evidence has also been obtained by Keilin and Mann (1937) and by Chance (1943, 1947) that peroxidase and catalase form complexes with their substrate, hydrogen peroxide. Although there is ample evidence that enzymes form compounds with their substrates, the nature of the interactions has remained largely unknown. From the viewpoint of the enzyme chemist,

THE CHEMICAL COMPOSITION OF CHLORELLA; EFFECT OF ENVIRONMENTAL CONDITIONS

The purpose of the investigations here described was to determine to what extent the chemical composition of a plant can be altered by growing it under different environmental conditions. The three general processes which determine the organic composition of a plant are photosynthesis, respiration, including aerobic and anaerobic catabolism, and biosynthesis. In the present state of knowledge it is difficult to discern to what extent these three processes are interrelated. For the immediate purposes of this investigation it is, in fact, not essential to attempt to determine which of these processes may be responsible for any observed changes in composition. If decided changes in composition are observable as results of altered environmental conditions, these effects can then be further analyzed and can perhaps ultimately be ascribed to one or another of the major processes. The immediate problem was to discover which environmental conditions would, when altered, affect the organic composition of the plant, and to determine the nature and magnitude of the effect. The objective was to find environmental conditions which would materially modify the relative proportions of the three major plant constituents, carbohydrates, proteins and lipids. For such an undertaking, very little information was available as a basis for a working hypothesis to aid in the choice of environmental conditions. It was obvious from the outset, therefore, that a large number of experiments would have to be made. In an investigation requiring many analyses, the determination of the organic composition of the plants in terms of definite chemical compounds, or even of groups of compounds, would be very laborious and time consuming. Regarding all of the organic carbon of the plant as arising from the of, carbon dioxide, we were more concerned with the energy level of this total organic matter than with the isolation of particular constituents. The determination of the heat of combustion of the plant material would, in a measure, satisfy this requirement; but such data would have a limited usefulness. Recourse was taken to a very simple means of determining the degree of reduction of the entire organic material of the plant from its elementary chemical composition. This general concept, which has been used but little in connection with problems of this nature,

CHROMOSIN, A DESOXYRIBOSE NUCLEOPROTEIN COMPLEX OF THE CELL NUCLEUS

A desoxyribose nucleoprotein complex, which we have referred to as a chromosin, has been prepared from a great variety of cells, mainly animal but also plant and bacterial. A chromosin is derived from the cell nucleus. In the course of preparation precautions have been taken to prevent contamination by cytoplasmic constituents. To assure the nuclear origin of all components of chromosin, nuclei have in several instances been isolated before extraction was begun. Because of the precautions taken, chromosins do not contain detectable quantities of ribose nucleoproteins; but, incidentally, extraction of ribose nucleoproteins, free of desoxyribose compounds, has also been described in this paper. A typical chromosin contains 3 components: desoxyribose nucleic acid, histone, and non-histone protein. The nucleic acid, being highly polymerized, is exceedingly viscous when dissolved and fibrous when precipitated. Histone and non-histone protein differ from each other in a number of ways, of which one of the most definite is that whereas a histone contains no more than traces of tryptophane, the non-histone protein of chromosin contains nearly 1 per cent of tryptophane. In neutral physiological saline both proteins can combine with nucleic acid. With the isolation of chromosins from so many different kinds of cells, it can now be seen that (contrary to the view expressed by Kossel) histones are present in most animal cells and at least in some plant and bacterial cells. Chromosin prepared from the Type III pneumococcus is active in transforming the type of a pneumococcus culture. It has been pointed out that it is not yet known whether or not protein is a necessary constituent of the transforming agent. To extract chromosin from a cell M NaCl is used. When dissolved in M NaCl the nucleic acid and histone components of a chromosin are to a considerable extent dissociated. They are not dissociated when the chromosin is dissolved in 0.02 M NaCl, but in this medium a partial depolymerization of the nucleic acid occurs. A chromosin should certainly not be considered to be a definite chemical compound. It is a complex extracted from chromatin, which is itself a complicated nuclear structure. And in the course of extraction, it need hardly be said, the structure of chromatin has been considerably changed. To avoid complications it has been considered an advantage in this work to begin with isolated nuclei, and it would clearly be a further simplification to begin chemical procedures only after the chromosomes themselves have been isolated. This is now being accomplished, and it is found that the methods described in this paper are of value in learning how the substances present in a chromosin are put together in a chromosome.

Further Experiments on Artificial Parthenogenesis in Starfish Eggs, with a Review

Previous articleNext article No AccessFurther Experiments on Artificial Parthenogenesis in Starfish Eggs, with a ReviewRalph S. LillieRalph S. Lillie Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 14, Number 3Jul., 1941 Article DOIhttps://doi.org/10.1086/physzool.14.3.30151604 Views: 2Total views on this site Citations: 12Citations are reported from Crossref Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). PDF download Crossref reports the following articles citing this article:John Runnström The Mechanism of Fertilization in Metazoa, (Nov 2006): 241–327.https://doi.org/10.1002/9780470122549.ch5J. F. Whitfield, A. D. Perris, T. Youdale The calcium-mediated promotion of mitotic activity in rat thymocyte populations by growth hormone, neurohormones, parathyroid hormone and prolactin, Journal of Cellular Physiology 73, no.33 (Jun 1969): 203–211.https://doi.org/10.1002/jcp.1040730306J.F. Whitfield, A.D. Perris, T. Youdale The role of calcium in the mitotic stimulation of rat thymocytes by detergents, agmatine and poly-l-lysine, Experimental Cell Research 53, no.11 (Oct 1968): 155–165.https://doi.org/10.1016/0014-4827(68)90363-7JOHN RUNNSTRöM The Vitelline Membrane and Cortical Particles in Sea Urchin Eggs and Their Function in Maturation and Fertilization, (Jan 1966): 221–325.https://doi.org/10.1016/B978-1-4831-9952-8.50010-9J. RUNNSTRÖM, B.E. HAGSTRÖM, P. PERLMANN Fertilization, (Jan 1959): 327–397.https://doi.org/10.1016/B978-0-12-123301-3.50015-XM. Sugiyama Physiological analysis of the cortical response of the sea urchin egg, Experimental Cell Research 10, no.22 (Apr 1956): 364–376.https://doi.org/10.1016/0014-4827(56)90009-X BIBLIOGRAPHY, (Jan 1956): 280–311.https://doi.org/10.1016/B978-1-4832-3292-8.50020-5Susumu Ito, Cecilie Leuchtenberger The possible role of the DNA content of spermatozoa for the activation process of the egg of the Clam, spisula solidissima, Chromosoma 7, no.11 (Jan 1955): 328–339.https://doi.org/10.1007/BF00329731LESTER GOLDSTEIN A STUDY OF THE MECHANISM OF ACTIVATION AND NUCLEAR BREAKDOWN IN THE CHAETOPTERUS EGG, The Biological Bulletin 105, no.11 (Sep 2016): 87–102.https://doi.org/10.2307/1538558 Drusilla Harding Initiation of Cell Division in the Arbacia Egg by Injury Substances, Physiological Zoology 24, no.11 (Sep 2015): 54–69.https://doi.org/10.1086/physzool.24.1.30152102Gunnar Lundblad Proteolytic activity in sea urchin gametes, Experimental Cell Research 1, no.22 (Jan 1950): 264–271.https://doi.org/10.1016/0014-4827(50)90038-3PAUL G. LEFEVRE CERTAIN CHEMICAL FACTORS INFLUENCING ARTIFICIAL ACTIVATION OF NEREIS EGGS,, The Biological Bulletin 89, no.22 (Sep 2016): 144–156.https://doi.org/10.2307/1538110

On maucherite (nickel-speiss, placodine, temiskamite) (With Plate XXIV.)

Nickel-Speiss (Nickelspeise), an impure arsenide of nickel obtained as a by-product in the manufacture of smalt, has long been known as a source of distinct crystals representing a definite chemical compound. Such crystals were already analysed by Döbereiner (1823), who concluded that the material was an artificial form of niccolite, NiAS. Later analyses showed that the composition of the crystallized furnace product approaches Ni3As2, a compound unknown in nature at that time.A substance corresponding to the crystallized nickel-speiss, but thought to be of natural origin, was first described by Breithaupt (1841), who named the material Plakodin (πλăκώδης, broad) in allusion to the tabular habit of the crystals. These were said to have occurred in the Jungfer mine at Müsen in Westphalia, associated with chalybite and gersdorffite and to have been salved by a smalt-works official from a shipment of ores.

A STUDY OF CRUDE COAL TAR AND ALLIED SUBSTANCES

In dealing with the problem of one must first define what is meant by tar. To use the term tar as if it were a definite chemical compound, readily obtainable from the pharmacist, is erroneous. A brief resume of the present, somewhat limited, knowledge of tars in general will illustrate this. Much of the information has been gathered from the writings of Porter 1 and Perutz and Siebert. 2 Since the latter authors have covered all the older literature on the subject we shall not cite it here. A few of the more recent publications have been cited by Nelson and Osterberg. 3 Any product obtained by destructive distillation of organic substances is a tar. It is thus readily understood that the chemical composition of tars varies with the substances from which they were derived and with the temperatures to which they are subjected. There are four main groups

The Influence of Catalysts in the Reaction of Sulfur on Unsaturated Organic Substances. I. A Study of Vulcanization at Elevated Temperature

Abstract From these results it might be thought that in the presence of potassium xanthate or hexamethylenetetramine there is formed a compound of sulfur and cinnamate containing one atom of sulfur per molecule of the ester. This compound would not be identical to that found by Baumann and Fromm, which was mentioned in Section 1. It has been seen that it is formed at a higher temperature and that it contains two atoms of sulfur per molecule of the ester. We attempted to isolate the compound containing one atom of sulfur, the existence of which we suspected. To this end, we distilled under reduced pressure (13 mm.) the product extracted with acetone. However, at 143° C. the ethyl cinnamate distilled almost quantitatively, whereas the sulfur remained in the residue from the distillation. Moreover, we observed a very intense Tyndall effect in the acetone solution. Several reasons for these phenomena suggest themselves: 1. The compound formed is stable only in equilibrium with its components. By distillation the cinnamate is eliminated, equilibrium is destroyed, and the compound is quantitatively decomposed during distillation. 2. Upon the addition of acetone, with a view to extracting the substance, the compound is destroyed and the sulfur which is precipitated in the colloidal state is dissolved with ethyl cinnamate in the acetone. In the acetone solution, therefore, the cinnamate and colloidal sulfur are found in stoichiometric proportion. This would explain both the equivalence which was found and the colloidal aspect of the acetone solution. 3. A definite chemical compound is not formed, purely colloidal natural phenomena are involved, and the stoichiometric relations must he due purely to chance. We shall not pay any particular attention at this time to experiments which would lead to a choice among these explanations. They will be the object of a future work. Nevertheless it seems of interest to us to note the parallelism between the vulcanization of rubber and the sulfuration of a well-defined unsaturated compound, and particularly the action of catalysts of vulcanization. Finally another important similarity may be pointed out. In the case of vulcanized rubber, a definite compound has not been isolated. It is likewise known that sulfur, which alone is insoluble in acetone, passes over in large quantity when extractions are made with this solvent. The question has always arisen whether this is a case of phenomena of a colloidal nature or of the formation of chemical compounds. We shall continue our work with a study directed particularly to simple cases where the starting compounds are well-known ones. Our efforts will be especially directed to the existence or non-existence of definite compounds. We have pointed out in this first article the difficulties before us. We shall then continue with studies of isoprene and methylbutadiene. It is conceivable that by the progressive polymerization of these products the complex case of rubber will finally be reached.

Oxide films on liquid metals studied by means of electron-diffraction

Electron-diffraction patterns obtained by reflection from molten lead, zinc, bismuth and tin have shown that the surfaces of these metals are covered with thin oxide films. From these patterns it has been deduced that the films consist of small electron-optically flat oxide crystals resting on their [001] faces. The inner potentials and crystal structures of these oxides have been found, and they have thus been identified as definite chemical compounds. It has also been found possible to remove these films from the molten metal by means of nickel gauze and to obtain electron-diffraction patterns by transmission. The transmission patterns indicate that although the removed films are of the same chemical composition as those on the molten metal, their removal has disturbed the orientation and given the crystals an approximately Maxwellian distribution of orientations about their original direction.

THE INSECTICIDAL PROPERTIES OF SOME EAST AFRICAN PLANTS. I

Summary.A number of East African plants, mostly indigenous, has been tested for insecticidal value as contact poisons.No new insecticide equal in toxicity to nicotine has been discovered.Two plants, Cassia didymobotrya and Barringtonia racemosa, have toxic properties slightly less than half that of nicotine used as sulphate. The plants, which grow dd, should be of value for making insecticides on those farms where they are already growing: they would not, however, be worth cultivating. No definite chemical compounds were obtained from these two plants.The toxicity of extracts of Tephrosia vogelii has been found to be of the same order as that of nicotine in the form of sulphate, and these extracts should be able to replace nicotine in all sprays against soft‐bodied insects such as aphis and thrips.Nearly all parts of this plant contain tephrosin, the seeds having the largest content at 0.35 per cent., whilst the leaves contain 0.18 per cent. Methods are given for the easy extraction of tephrosin from the various parts of the plant. The product obtained has been called “crude tephrosin ” by the author, and in this form is suitable for the preparation of insecticides.Crude tephrosin contains about 20 per cent. of a substance crystallising in he yellow needles with a melting‐point of 227° C., which is probably dehydrodeguelin and is non‐toxic. The remaining 80 per cent, forms white tabular crystals with a melting‐point of 187° C., and is undoubtedly identical with Hanriot's tephrosin. So far it has resisted separation into two or more constituents, either by repeated recrystal‐lisation or by oxidation. This crystalline substance accounts for the toxicity of the crude tephrosin and of the plant itself.Resins were obtained from most parts of the plant but, contrary to Tattersfield's results, they were found to be only slightly toz.It is considered that in view of the fact that Tephrosia vogelii grows both widely spread and vigorously in East Africa it should be able to replace the use of nicotine almost entirely. On a small scale home‐made solutions could be easily and cheaply prepared, and the extraction of crude tephrosin on a larger scale is also worth consideration.9. As a paraffin spray agarnst Antestia and Lygus, Tephrosia vogelii extracts proved useless compared with pyrethrum, but as a domestic spray against flies, mosquitoes, etc., paraffin extracts were found to be as effective as pyrethrum and should be able to replace it, at least for local use.10. The finely powdered pod of T. vogelii has some value as an insect powder, due probably to the tephrosal in it, but cannot compare with pyrethrum powders.11. The seeds contain 12 per cent. of fixed oil from which a soft soap can be made, suitable, according to preliminary tests, for a spreader but not for domestic purposes. The oil is a non‐drying one.12. Further work on many of these points is continuing.

The Study of Specific Combination in Immunity Reactions

IT can scarcely be denied that up to the present the study of immunity reactions has been especially difficult owing to current theories being most vague and conflicting. As a result much of the work done has shown a lack of method and definite line of attack. It seemed to us that if a reaction, in which at any rate one of the reacting substances was a definite chemical compound, could be studied, this would form a sound basis for further investigation. This we have attempted to do.

The behaviour of electrolytes in mixed solvents. Part II.—The effect of lithium chloride on the activities of water and alcohol in mixed solutions

In the interaction between ions and solvent molecules, two types of physical effects have been recognised. The first, solvation, may be ascribed, in the absence of definite chemical compound formation between the ions and the solvent, to the attraction exerted by the electric field of the ions on the polarisable molecules of the solvent. Since the elements of a polarisable medium tend to move into those regions where the electric field is greatest, the molecules of water in aqueous salt solutions will tend to congregate round the ions and will be held by quite considerable forces. In the presence of second substance, having a lower dielectric constant than water, this gives rise to the second or salting-out effect. Since water molecules are attracted by the ions more strongly than those of the other substance, the latter may be displaced or salted-out from the vicinity of the ions and their activity in the solution consequently increased. This effect has been extensively studied in dilute aqueous solutions either by means of solubility measurements with sparingly soluble non-electrolytes or by experiments on the distribution of the non-electrolyte between the aqueous solution and an immiscible solvent in which the electrolyte is not soluble.

X-ray Studies on the ‘Nitrides’ of Iron

EXPERIMENTS made by Fowler, Baur and Voermann, White and Kirschbraun, and Tschischewski show that iron ‘nitrides’ with a maximum amount of about 11 per cent nitrogen are formed when ammonia is led over heated iron. The most favourable temperature for the reaction seems to be about 450° C. Some of the authors are of the opinion that definite chemical compounds, that is, nitrides, are formed, while others consider the products to be solid solutions of nitrogen in iron. Studying the ironitrogen system by means of X-rays, I have found the latter opinion to be the correct one.

Roentgenological Exploration of Spinal and Cerebral Spaces, Genito-Urinary Organs and other Organic Cavities with Iodized Oil

SINCE 1921, when we showed the possibilities of an iodized oil, called lipiodol (Lafay), as an opaque mediun, for roentgenologic exploration, we have extended the use of the preparation to a great many cavities of the body. At the same time, French and foreign investigators, taking advantage of our initial work, succeeded in enlarging the field of our general method. Besides the two principal roentgenological uses of lipiodol—exploration of the central nervous system (spinal subarachnoid space and cerebral ventricles) and exploration of bronchial tubes—there have occurred a great many uses of minor importance, but still quite promising. We shall review here the exploration of the different cavities, except those of the bronchial tree concerning which we have written already in Radiology.2 The Substance.—First, we must say a few words about the substance itself. Lipiodol is a definite chemical compound in which 40 per cent iodine is bound to a fat body—poppy-seed oil. It is not a solution: this is most important, and explains why, in spite of its high percentage of iodine, lipiodol is tolerated by human tissues and cavities as any ordinary oil. The injection of lipiodol, up to very high doses, hardly gives any reaction and generally no iodism, because there is no free iodine. Lipiodol is a clear, transparent, yellow oil, of high density and much thicker than olive oil. All samples of brownish color or dim appearance, containing free iodine, must be strictly avoided. The best lipiodol is delivered in small aluminum flasks, and, being antiseptic, does not require any sterilization. Lipiodol is much heavier than water and all body fluids. When injected into a duct or cavity it progresses generally to the lowest part, according to the action of gravity, in very small ducts or tubes the action of capillarity stops this progress. Epidural Space.—The exploration of this region, between the spinal theca and the spine itself, is of great interest in all bony diseases of the spine, for early modifications here are frequently apparent. Lipiodol may be injected through the lower method “Sicard's sacrococcygeal,” or through the lumbar or cervical regions. In the latter case, the technic is the same as for a lumbar puncture, but it is important that the point of the needle, after penetrating the ligamentum flava, should not perforate the theca.3 Four to six c.c. of lipiodol may be injected, which, by its specific gravity, will slide slowly down the space toward the coccyx, leaving a deposit resembling, in the film, irregular and elongated splotches of ink. If, after the injection, the patient is put in Trendelenburg's position, it is clear that the lipiodol will slide down toward the thoracic vertebrzæ, the length of the track being determined by the quantity injected (Fig. 1).

Roentgenological Exploration of the Bronchial Tubes with Iodized Oil (Lipiodol)

THE use of a new means of contrast for radiological exploration has been, in every case, in correspondence, in some respects, with practical improvements: for example, the opaque solutions of sodium bromide have been helpful towards a better knowledge of the pathology of the kidney pelvis and ureters, and the discovery of pneumoperitoneum for radio-diagnostic purposes has increased our findings in pathology of the abdominal organs. Four years ago we began methodically to use as an opaque fluid for radiology an iodized oil (lipiodol) which French and foreign physicians had been injecting for many years in cases where a chronic iodine treatment was to be carried out. In fact, many physicians had noticed that this oil, being injected subcutaneously or intramuscularly, gave, in radiograms, large opaque spots, which remained visible for a long time, though no clinical symptom of the presence of the oil could be observed. The original part of our work was to take advantage of the qualities of lipiodol—high opacity to X-rays and perfect tolerance by human tissues—and to use it as a means of contrast for the radiologic exploration of cavities which it had been impossible to explore with methods previously in use. Our first experiments were made on the cavities of the spine, epidural and subarachnoid spaces, but soon after, realizing the wonderful innocuity of lipiodol, we found that it would be well tolerated by the respiratory mucous membrane and could be introduced by intra-tracheal injections. Our first attempts on animals (rabbits and guinea pigs) proved to us that lipiodol could be injected into the bronchial tubes without more danger than any ordinary oil. In January, 1922, with our friend L. Le-roux, we succeeded in getting the first film of the bronchial tubes of a living subject, a film which, for the first time, was purposely and harmlessly obtained. Before describing the technic and results of the method, we shall say a few words about the drug itself. Lipiodol Lipiodol is vegetable iodized oil, containing 40 per cent of iodine, this high percentage explaining the favorable opacity of the substance to X-rays. It is important to note that lipiodol is not a solution of iodine in vegetable oil, but a definite chemical compound in which the halogen cannot be detected by ordinary reactives. This explains why, in spite of its high concentration in iodine, lipiodol is so wonderfully tolerated in the cavities of the body; as there is no iodine free in lipiodol, this one does not produce any irritation or toxicity, as any iodine solution is expected to do. Lipiodol is a fine, pure, transparent oil, a little darker in color and much thicker than olive oil.

Some Chemical Influences in regard to the Endocrine Glands and the Central Nervous System

Mr. President, Ladies and Gentlemen,—In view of what has already been said to-day I am afraid that anything which I may be able to contribute to this discussion will be superfluous, but perhaps, by approaching the subject from the point of view of the influence of certain chemical substances on the general function of the animal organism, an additional side-light may be obtained on this subject. It is difficult to separate many of these chemical actions, as the functional activity of the endocrine glands and the nervous system are so intimately connected. In addition the active principles of some of the endocrine secretions are now identified as definite chemical compounds closely allied to other substances which may possibly be produced in the organism under pathological conditions.