348 SUMMARY OF CUEKENT RESEARCHES RELATING 10 



Reproductive Organs and Larvae of Warble Fly.* — G. H. 

 Carpenter -and Thomas E.. Hewitt describe the ovaries and oviducts, the 

 accessory glands and spermathecge, the ovipositor, and the male genital 

 aperture in Hypoderma bovis. The ovaries are remarkable on account 

 of the arrangement of the ovarioles. Each is made up of more than a 

 hundred ovarioles, e.g. 120 in the right ovary and 110 in the left, and 

 three or four eggs may be developed in each. A single female would 

 thus produce about 800 eggs. There is definite specific difference 

 between the male genital aperture in H. bovis and H. lineatum. The 

 authors induced a captive female to lay eggs on a calf's hairs in a glass 

 tube. Eggs kept in an incubator at 40° C. hatched in four and a half 

 days. 



Independently of Glaser the authors have described the newly 

 hatched maggot of Hypoderma bovis — a very interesting type of insect 

 larva with formidable mouth-hooks and strong spiny armature. There 

 are seven or eight irregularly arranged rows of spines around most of 

 the segments, two or three series of strong spines being found close to 

 the front edge of each segment, those behind being feebler, and the 

 posterior margin of each segment showing a strip free from spines. 



Spermatogenesis in Lepidoptera.* — L. Verlaine has investigated 

 the origin of the different intrafollicular cells and their mutual relations 

 in Lepidoptera, and especially in Arctia caja. The testicular follicles 

 exhibit three kinds of cellular elements well-defined by their form and 

 function : Verson's cells, the sex-cells, and the cells of the cyst mem- 

 branes. At the moment of division of the capsule into four follicles a 

 Verson's cell appears in each follicle ; it is therefore not a mother-cell 

 of the sex-cells and it does not arise from a cell of the testicular envelope. 

 It is a primordial, spermatogonium which is modified synchronously in 

 the four chambers of the two testicular capsules of a caterpillar by the 

 influence of factors still unknown. The Verson's cell elongates and 

 becomes pedunculated in such a way as to be isolated in the centre of 

 the mass of primordial spermatogonia, while remaining fixed by its 

 stalk to the testicular envelope for a relatively long period. This giant 

 cell is of very variable outline ; it takes the form of the space in which 

 it rests. It is always separated by membranes from the living sex-cells 

 which surround it, but in the later stages degenerating sex- cells or 

 clusters of these are engulfed and assimilated by its cytoplasm. Its 

 nucleus does not divide by karyokinesis. During the stalked stage the 

 giant cell rarely shows peripheral cytoplasmic granules ; these only 

 appear when the absorption of disintegrating cells has begun. These 

 granules, which are thus cellular in origin, are destined to dissolve, and 

 they never pass directly into the sex-cells, which are everywhere enclosed 

 by a membrane. The giant cell finally disintegrates and its remains 

 mingle with the intrafollicular liquid. 



In the early stages the primordial spermatogonia are few in number, 

 but they multiply rapidly and crush each other. They elongate or 

 become pear-shaped and form a more or less regular layer surrounding 



* Sci. Proc. Roy. Dublin Soc, siv. (1914) pp. 268-89 (6 pis.). 



t Bull. Acad. Belgitjue, Classe Sci., 1913, pp. 701-54 (5 pis. and 2 figs.). 



