

1891.] Variations observed in the Rabbit's Liver. 209 



Pteroplatcea micrura, Myliobatis nieuhofii, Tri/gon walga, and Trygon 

 bleeJceri, the large wide-open spiracles. In Pteroplatcea we know that 

 the trophonemata pass into the spiracles ; but the singular distension 

 of these orifices in the other species, in contrast to the smallness of 

 the other apertures of the body, points to the conclusion stated. 



4. The stomach in all cases that we have hitherto observed (except 

 in Trygon bleekeri, where the observation was lost) is empty, small, 

 and displaced ; while the colon (spiral gut) is full, large, and dis- 

 tended at the expense of other organs. And this leads us to the 

 conclusion that the foetal stomach is simply a channel through which 

 the easily assimilable food passes to be absorbed by the spiral gut. 

 And of this conclusion the presence of the unchanged " milk" in the 

 spiral gut of Myliobatis is corroborative. 



5. Finally, as to the method of respiration of the foetus, no conclu- 

 sion can as yet be arrived at. It is probably safe to assume that the 

 consumption of oxygen and the production of carbonic acid by the 

 foetus are comparatively small, and that the respiratory exchanges 

 are sufficiently carried out through the soft foetal skin where this 

 comes in contact with the vascular trophonemata and uterine wall. 



Hitherto, we have not found any special distribution of blood- 

 vessels to the skin, in the foetus. And in Pteroplatcea the manner in 

 which, when two foetuses are present, the one is rolled up within the 

 other, prevents contact of the inner foetus with the uterine wall, 

 except at the snout, and where the trophonemata enter the spiracles. 



We are indebted to Professor G. B. Howes for calling our atten- 

 tion to a short note by Dr. W. A. Has well *(* Proceedings Linnean 

 Society, New South Wales,' vol. 3, 1889, pp. 1713 to 1716) on 

 Urolophus, in which it is suggested that the extraordinarily long 

 external gills of the foetus are concerned in absorbing matter which 

 is supposed to exude from the blood-vessels of the uterine villi. 



IV. " On some of the Variations observed in the Rabbit's Liver 

 under certain Physiological and Pathological Circum- 

 stances." By T. LAUDER BRUNTON, M.D., B.Sc., F.R.S., 

 and SHERIDAN DELEPINE, M.B., B.Sc. Received October 

 22, 1891. 



(Abstract.) 



Under the influence of the natural stimulus of digestion, numerous 

 changes are observable in liver cells. In this we partly confirm 

 and partly complete (and add to) the observations of previous 

 investigators. 



