Indigestible Material Research Articles

A Biological Application of Röntgen Photography

THE accompanying Röntgen radiograph of Astropecten irregularis was made in the physical department of this college, for a popular lecture on the new photography given by Prof. H. Stroud. It will be seen that not only are the ossicles of the oral surface fairly successfully shown through the thickness of the body and arms, markedly the first of the series of adambulacra, but certain striking and unlooked-for objects appear as well. On dissection the dark conical body to the right proves to be a large piece of the shell of Dentalium lying in one of the cæca of that arm. The oval bodies, one in each of the cæca of the opposite arm, are masses of sand and indigestible material enclosed in the thinned shells of molluscan victims. These are made by the action of the cilia, and form a convenient way of getting rid of the useless matter by way of mouth. The minute anus, indeed, is quite inadequate, and is doubtless used more for fluid than solid evacuation. The madreporite plate and stone canal are seen in the inter-radius below and between the bodies referred to; and the position of the stone canal was in fact the guide in determining their position. The darkish mass in the cæcum to the left of the stone canal consists mainly of broken and whole shells of young Cardia. The stomach was filled with a whole common mussel (Mytilus edulis), minus the shell, and this is quite transparent. The paxillæ will be seen to occur as dots all over the body and arms. A block of wood, which was laid over part of the star-fish, has evidently only made a part of the picture lighter.

Aerated Bread

SOME remarks upon aerated bread which were made by Dr. B. W. Richardson at the recent general meeting of the company working Dr. Dauglish's patents require examination. Now it is noteworthy how imperfect our knowledge of the chemistry of the mill-products from the cereal grains still remains. Without such knowledge we are not in a position to dogmatise as to the exact nutritive values of different kinds of bread. As I pointed out in a previous article on “Real Brown Bread,”1 the statement that whole wheaten meal, bran, pollard, &c., contain more nitrogen, and therefore more flesh-formers than fine flour, rests upon no certain basis of analytical fact. And if it were proved that all the nitrogen of the most nitrogenous of mill-products does really exist in what are called albuminoids or flesh-formers, we cannot ignore the presence of much indigestible fibrous material in bran and pollard, material which is not only non-nutritive itself, but which locks up in an inaccessible form much of the real nutrient substances associated with it. Thus a sample of wheaten. bran, or rather, fine pollard, may refuse to give up to the boiling dilute acid and alkali used in fibre-determinations more than six-sevenths of its nitrogenous matter; and it can hardly be expected that the secretions of the alimentary canal will prove successful in withdrawing a larger proportion. Indeed, the analysis of the residues of such foods after having been submitted to the digestive process, has confirmed this expectation in the case of the human subject. Moreover, while a not inconsiderable part of the albuminoid matters of the outer coverings of the grain thus escapes digestion from its mechanical condition, there is good reason to believe that a further portion remains unabsorbed, by reason of the rather hurried passage of the branny particles through the digestive tract. And the same causes which operate to prevent a part of such flesh-formers as exist in the bran, from being utilised, affect also and in a similar way the useful mineral substances which abound in the coarser mill-products, as well as the oil or fat which they contain.

Biological Notes

NEW FRESH-WATER RHIZOPODS.—For many years the small group known as Actinophrys, first accurately described by Ehrenberg, remained somewhat isolated, distinguished among unicellular forms by its nearly constant spherical form, and the persistence of its straight radiating processes or “pseudopodia.” But in recent years a whole series of organisms has been described, and has attained sufficient prominence to constitute, with Actinophrys, an order denominated Heliozoa. Many interesting papers have appeared in the Archiv für mikroskopische Anatomie on these organisms, contributed by E. Hertwig, Lesser, Cienkowski, Greeff, and others; and in our own country Mr. W. Archer has been the most active and successful student of the Heliozoa, his papers having been principally published in the Quarterly Journal of Microscopical Science. From these one derives an idea of these animalcules as being the most complex of the free forms which possess pseudopodia, and are at the same time unicellular; they are neither multicellular and differentiated like the Radiolaria, nor organised like the ciliated Infusoria. While a few forms, as Actinophrys, are quite devoid of skeleton, most of them possess certain hard parts, consisting, it may be, of a single solid and globular piece, but in other cases of very minute rod-shaped spicules, sometimes siliceous, sometimes easily soluble. These are either disposed so as to invest the main body of the organism more or less closely, or radially, projecting as spines. When food is taken, these minute hard parts can be pushed aside to allow access to the central body-mass; and the same occurs when indigestible material is thrust out. Locomotion is usually very slow; most Heliozoans move by balancing themselves on the tips of their pseudopodia, and thus very gradually rolling onwards. Multiplication of the organisms is effected by division, either simple, or occurring after encystation. Some forms are remarkable for containing a great abundance of chlorophyll granules.