DEVELOPMENT OF THE P]G DURING FIEST TEN DATS. 357 



22. Rauber. — " Die erste Entwickelung des Kanincliens," ' Sitzungsbericlite 



der Naturforsclienden Gesellscliaft zu Leipzig,' 1875. 



23. KoBiNSONj A. — "Observations upon the Development of the Segmenta- 



tion Cavity, the Archenteron, the Germinal Layers, and tiie Amnion 

 in Mammals,' ' Quart. Journ. Mic. Sci.,' vol. xxxiii, 1891-2. 



24. ScHAFER, E. A. — "Description of a Mammalian Ovum in an Early 



Condition of Development," 'Proceedings of the Royal Society of 

 London,' 1876. 



25. Weysse, A. W. — "On the Blastodermic Vesicle of Sus scrofa 



domesticus," 'American Academy of Arts and Sciences,' vol. xxx, 

 1894. 



DESCRIPTION OF PLATES 25—28, 



Illustrating Mr. Assheton^s paper on "The Development of 

 the Pig during the First Ten Days." 



Complete List of Reference Letters. 



C. Bl. Cavity of the blastocyst. E. Epiblast. H. Hypoblast. /. M. Inner 

 mass. M.H.L. Membrana hypoblastica limitans. S.P. Spermatozoa. T. 

 Trophoblast. T. R. Trophoblast ceils which overlie the embryonic knob. 

 Z. Zona radiata. 



PLATE 25. 



Fig. 1 (Sus 25, No. 1). — Embryo of tlie pig in the two-segment stage. 

 Found in the uterus. Killed with Flemming's bolution. The oily globules 

 scattered throughout the inner part of each segment have been blackened by 

 the osmic acid. Age G days, x 380. 



Fig. 2. — Same embryo as the former, but seen edgewise, x 380. 



Fig. 3 (Sus 12, No. 1). — Embryo of pig in the three-segment stage. 

 Found in the upper part of the uterus. Examined and drawn while fresh. 

 Age 4 days, x 380. 



Fig. 4 (Sus 1, No. 1). — Embryo of pig in the four-segment stage. Found 

 in the Fallopian tube. Examined and drawn while fresh. Age three days. 

 X 380. 



Fig. 5 (Sus 12, No. 4). — Embryo of pig in the five-segment stage. Found 

 in the uppermost part of the uterus. Examined and drawn while fresh. Age 

 4 days. X 380. 



Fig. G. — Embryo of pig. Found in the uterus. Drawn after the specimen 

 had been treated with chromic acid. Age 6 days, x 380. 



