The works of Francis Maitland Balfour, Volume 3 (of 4)
CHAPTER VIII. AVES. Pp. 145-201.
Segmentation and formation of the layers, pp. 145-166. General history of the germinal layers, pp. 166-169. General development of the embryo, pp. 169-180. _Foetal membranes_, pp. 185-199. Amnion, pp. 185-191. Allantois, pp. 191-193. Yolk-sack, pp. 193-199.