Deep Constriction Research Articles

Action of periodate on the surface reactions attending the activation of the egg of the sea urchin, Psammechinus miliaris

A solution of jelly coat substance inhibits a normal differentiation of the fertilization membrane in eggs of Psammechinus miliaris. The contraction of the egg surface does not occur, the coagulation of the vitelline membrane and the merging of the cortical material with this membrane are impeded. Furthermore the eggs present a varying degree of di- or plurispermy in presence of jelly coat solution. All the effects of the jelly coat solutions which have been mentioned in the preceding paragraph are removed by addition of 5 × 10 −5N sodium periodate. Periodate has also a certain activating effect on the ripe eggs. Particularly it sensitizes the egg to the activating effect of brief exposures to hypertonic medium. Pretreatment of underripe eggs with periodate has a most striking improving effect on membrane formation and further development. The jelly coats of periodate pretreated eggs are more weakly precipitated upon addition of clupein than are eggs not pretreated. Periodate treatment has a harmful effect on the oocytes. They elongate and a deep constriction separates the oocyte into one nucleated and one non nucleated part. Numerous bulges and appendages are formed from the latter (Fig. 11). It is inferred that underripeness is caused by the predominance of an inhibitor having a character similar to that of the jelly coat substance. The belief is expressed that the inhibitory agent is deeply engaged in the whole activation process.

Report on a Collection of Branchiobdellids

Cambarincola macrocephela n. sp. (Figs. 1 and 2) Description: Cambarincola: Worm cylindrical, head large, expanded so that it is distinctly wider than anterior body segments. Head separated by deep constriction from Segment I. Dorsal lip with four finger-like projections, ventral lip entire. Body segments increasing in width from I to VII, posteriorly decreasing to the terminal sucker. Major annulations of body segments not elevated over minor annulations. Ventral and dorsal jaws similar, appearing as large triangular blocks of chitin terminating in sharp tooth. Without lateral teeth but margin uneven. Width of jaws at base 400 ,R. Pharyngeal diverticula four, two dorsal and two ventral. Alimentary canal in medial portion straight, with large sacculation in segments II and III and small sacculations in segments IV, V, VI and VII. Posterior to segment VII, narrows rapidly to anus in dorsal portion of segment X. Testes in pairs in segments V and VI. Vasa deferentia joining atrium in VI; with accessory sperm tube. Ovaries in segment VII. Length of mature worm 2.0 to 4.0 mm. Locality: Polecat Creek, Northern Teton County, Wyoming, August 16, 1941. Coll. Robert C. Brown. Host: Astacus gambellii. Holotype specimen: U. S. Nat. Mus. Coll. No. 20598.

A New Imperfect Fungus

While making a study of the organisms associated with a root and collar rot of pear trees in Louisiana, a fungus with very characteristic spores was isolated from the dead bark. This fungus apparently does not fit in any of the described genera of fungi and consequently a new genus is erected for it. The outstanding peculiarity of this fungus is the form of the conidia. These are wedge-shaped with very deep constrictions and resemble the common illustrations of Christmas trees

The Adult Form of the “Harvest Bug”

THE adult form of the larval mite known as the “Harvest Bug” (Leptus autumnalis Shaw), which causes so much annoyance in many rural districts at this time of the year, has long been sought for. In the middle of August, Prof. F. V. Theobald and Mr. C. W. Goode, of Wye, sent me three chickens heavily infested with this larval mite. From these larvae I have succeeded in rearing an adult mite closely allied to Trombicula, Berlese, and resembling that genus in having a deep constriction behind the anterior pairs, of legs, but more elongated in form and with the setae on the cephalothorax shorter and differently shaped. I propose the name Trombicula (Neotrombicula) autumnale for this adult mite, Neotrombicula being a new subgeneric name. The name Leptus was created by Latreille for Acarus phalangi (= Achorolophus ignotus Oudmns), now referred to the family Erythraeidae, and should not be used for the “harvest bug”, which belongs to the family Trombidiidae.

The hunger mechanism in birds. (Preliminary report.)

Both normal and decerebrate pigeons have been used in this study. Hunger is marked by the appearance of restlessness. This restlessness appears before the crop is completely empty. Lack of water even though the crop be distended with dry food is marked by restlessness of the bird. These things are true of birds with cerebrum intact, partially, or wholly removed. During hunger, changes occur in the behavior of the crop. In the normal bird with “appetite”(?) satisfied or at least in the bird which does not of its own accord eat of an abundant food supply, the crop is very much distended. In this condition only occasional contractions of the organ can be detected by means of a rubber balloon; none are visible to the eye (after removal of the feathers over the crop). An hour or two after feeding there begins to appear in the crop contractions in groups of three or four at intervals of 15-20 minutes. The activity of the crop is gradually augmented and 8-12 hours later there occur groups of 8-20 contractions at intervals of 10-30 minutes. Still later in some birds (probably young) the crop is in a state of almost continuous activity. When the content of the crop has been lessened to about one third of its capacity these contractions are directly visible. At this time they may be seen to involve principally the lower part of the crop. When it is completely empty these contractions are periodic in groups of 8-16 occurring at intervals of 10-60 minutes. Each contraction may be seen to begin at the upper part of the crop and sweep as a deep constriction, preceded by a marked bulging or relaxation, over the entire crop (and probably down to the gizzard).