278 SUMMARY OF CURRENT RESEARCHES RELATING TO 



depend on mechanical pressure conditions. The fat in tlie testis is 

 "probably not formed by the interstitial tissue at all, but is brought there 

 by the circulation and deposited. 



The conclusion arrived at is, that there are no " interstitial cells " in 

 the testis of the chicken in the sense in which the term is technically 

 used. Xor is there any evidence of an internal secretion of any kind 

 formed by any cells of the interstitial tissue. This result would appear 

 to derive interest in consideration of the fact that in few animals is 

 there so extensive a development of secondary sexual characters as in 

 the male of the domestic fowl. 



Endocrinal Testicular Tissue in Urodela.* — C. Champy finds in 

 newts, salamander, and axolotl, a glandular endocrinal tissue, localized 

 in the testes around the spermatocysts, appearing as they are expelled, 

 and disappearing at the height of the spermatogenesis. It might be 

 compared to a testicular corpus luteum. It develops at the expense of 

 connective-tissue cells. The various changes are described. It has no 

 direct action on the secondary sex-characters, which develop before it 

 appears, but the secretion may have some other sexual influence. 



Early Stages in the Development of the Hedgehog.f — Th. Bau- 

 meister gives an account of the establishment and structure of the 

 two primary germinal layers in the hedgehog. The spot at which there 

 seems to be the first trace of a modification of the diploblastic germinal 

 disk is almost central, and this spot is the focus of the subsequent 

 formative processes. From this spot the median proliferation of the 

 ectoderm known as the primitive streak progresses towards the posterior 

 end of the area embryonaiis. It is shown that the primitive streak is 

 the matrix for the whole middle layer — a very important conclusion. 



Development of Thymus of the Sparrow. J — C. Helgesson finds 

 that in Passer domesticus the thymus is a pure endodermal thymus, 

 arising from the ventral and dorsal wall of the third cleft. The median 

 part of the same forms the third parathyroid body. In the transforma- 

 tion of the giU-cleft into a thymus vesicle, the inner end of the third 

 ectobranchial duct comes very close to it, but it atrophies without 

 taking a share. For a relatively long time the thymus primordium 

 retains its single character and grows into a long strand. Its division 

 is conditioned by the nerves (hypoglossal and ventral cervical nerves) 

 which cut into it. As the thymus grows, the third parathyroid passes 

 from its d(U'sal position to a ventral one, which seems to be its primary 

 position in the fowl. 



The lateral portion of the fourth gill-cleft is constricted off as the 

 fourth parathyroid. With this is associated the tip of the fourth ductus 

 ectobranchiahs, which atrophies without leaving a trace. The post- 

 branchial body is due to the median part of the fourth gill-cleft. It 

 atrophies on the right and is quite gone by the 14 mm. stage. On the 

 left it may be seen in the adult as a thin plate of trabecular glandular 



* C.R. Soc. Biol. Paris, Ixxiv. (1913) pp. 367-8. 



t Zeitschr. wiss. ZooL, cv. (1913) pp. 1-86 (2 pis. and 10 figs.). 



X Anat. Anzeig., xliii. (1918) pp. 150-72 (8 figs.). 



