412 SUMMARY OF CUEKENT KESEARCHES RELATING TO 



Segmentation of Ovum in Hedgehog* — E. Ballowitz contributes 

 some facts regarding tlie early stages of development in this animal. 

 Segmentation does not proceed in strictly geometric progression. The 

 €gg plasma divides within the zona pellucida into 3, 6, and 7 blastomeres 

 which are very unequal in size. At other stages also differences in the 

 size of the blastomeres are observable. At the i-celled stage the egg 

 lies in the middle third of the oviduct. The corona radiata of the 

 follicle cells is lost during the passage of the egg through the oviduct ; 

 in the 8-celled stage its last remains have disappeared. At this stage 

 the egg enters the uterus, and it may enter earlier. The zona pellucida 

 is still intact. In no case, except as regards size, is there any differentia- 

 tion suggestive of ecto- and endoderm at this stage. 



Zonal Blastoderm.f — Jan Tur has observed this peculiarity in fowl 

 and crow, and gives a somewhat different interpretation from that of 

 M. Loisel, who attributed the phenomenon to the penetration of 

 spermatozoa in the equatorial region of the egg without fertilisation of 

 the germ. According to the author a zonal blastoderm represents the 

 peripheral part of a blastoderm resulting from normal fecundation, 

 whose central part has secondarily been destroyed. It is, in fact, a 

 pathological condition, and he describes the different stages through 

 which the zonal condition is arrived at. 



Size of Litter in Poland China Sows.| — G. M. Rommel and 

 E. F. Philipps show that this breed of sows has increased in fertility 

 (0'48) during the twenty years between 1882 and 1902. The statistics 

 show that the size of litter is a character transmitted from mother to 

 daughter. It would appear that by judicious selection of sows from 

 large litters, the average for the breed may be increased. 



Determination of Sex in Rabbits.§ — Achille Russo submits the 

 results of experiments which seem to show that the number of females 

 produced can be greatly increased by sub-cutaneous or intra-peritoneal 

 injections of lecithin. 



Cervical Plexus of Sturgeon.|l — A. Ostroumoff continues his studies 

 of the development of the sturgeon, dealing in the present instance with 

 the formation of the cervical plexus. He concludes that the N. hypo 

 glossus arises from the ventral roots of the nerves of the 4th and "sth 

 myotomes (10th and 11th roots of van Wijhe). Other nerves dealt with 

 in the paper are the Plexus pterygalis and the Nervus prozonalis and its 

 branches. 



Development of Diaphragm and Stomach of Ruminants.1i — 

 K. Wolf er makes a contribution to this subject. The diaphragm develops 

 in sheep, cattle, and goats, as in other mammals, except that the relations 

 of the pleuro-peritoneal membrane to the primitive kidneys are much more 



* Anat. Anzeig., xxix. (1906) 647-8 (8 figs.), 

 t Comptes Rendus, cxliv. (1907) pp. 992-5. 

 t Proc. Amer. Phil. Soc, xlv. (1906) pp. 244-54. 

 8 Atti (Rend.) R. Accad. Lincei Roma, xvi. (1907) pp. 362-8. 

 Il Zool. Anzeig., xxxi. (1907) pp. 723-5 (1 fig.). 

 ^ Anat. Anzeig., xxx. (1907) pp. 257-70 (11 figs.). 



