540 SUMMARY OF CURRENT RESEARCHES RELATING TO 



go to show that the growth of the niamrnaiy glands during pregnancy 

 is due to the action of a specific chemical stimulus produced in the 

 fertilised ovum. The amount of this substance increases with the 

 growth of the foetus. Lactation is due to the removal of this substance, 

 which is regarded as exerting an inhibitory influence on the gland-cells, 

 hindering their secretory activity and furthering their growth. It is 

 also suggested that the specific substance is diffusible. It is not claimed, 

 however, that these conclusions are as yet firmly established. 



Placenta of Tragulus.* — Ciro Barbieri finds that the placenta of 

 Tragulus meminna is typically diffuse, like that in pigs and horses. In 

 Tr.javanicus there is this slight difference, that there is a partial atrophy 

 of villi on the antimesometral side of the uterus. The superficial 

 internal layers of the uterus are extraordinarily rich in leucocytes, which 

 continuously engulf and assimilate the epithelial cells of the placental 

 villi. 



Breeding Habits of Pipe-Fish.t — E. W. Gudger gives an interesting 

 account of the " Liebesspiel " of Siphostoma floridce preparatory to the 

 act of copulation. Both sexes swim around with their bodies in nearly 

 vertical positions, but with head and shoulders sharply bent forward like 

 the letter /. " Then they swim slowly past each other, their bodies 

 touching, and the male being perhaps more demonstrative. Just before 

 the actual transfer, the male becomes violently excited and demonstra- 

 tive, shakes his head and anterior body parts in a corkscrew fashion, and 

 with his snout caresses the female on the belly. The female responds to 

 this, but does not become so excited. This is repeated several times, the 

 fishes becoming more excited each time they touch each other. Presently, 

 quick as a flash, the sexual embrace takes place, and then the fishes 

 separate to begin again in a few minutes." The embrace consists in the 

 fishes intertwining their bodies like two letter <S"s, the one reversed on 

 the other, thus bringing them face to face. Thus they hold their 

 bodies together while the eggs pass from the oviduct into the pouch of 

 the male, fertilisation presumably taking place at this moment. Before 

 the complete transfer is effected several contacts are made. The process 

 is so carried out that any contact of the eggs and sperms with the sea 

 water is absolutely prevented. The pouch and its contents appear to 

 act as a " physiological placenta " ; the eggs and embryos depend on it 

 for oxygen and food, and cannot survive out of it. The author has 

 followed the segmentation of the egg through a considerable number of 

 stages, and these he describes. 



6. Histolog-y. 



Nerve-Endings in the Lung.J — F. Ponzio concludes that in the 

 lung there are no true nerve terminations. There are terminal net- 

 works which envelop and interpenetrate the cells investing the minute 

 bronchioles, the alveoli, and the capillaries. The richness and intricacy 

 of this nervous apparatus are probably an index of its great functional 

 importance. 



* Anat. Anzeig., xxviii. (1906) pp. 327-36 (5 figs.). 



t Proc. U.S. National Museum, xxix. (1905) pp. 447-500 (7 pis.). 



X Anat. Anzeig., xxviii. (1906) pp. 74-80 (1 pi.). 



