528 A. A. W. HUBRECnT. 



the allantoidean tropLoblast is beginning to be applied against the uterine 

 epithelium. 



Fig. 21.— Utr. Mus. Cat. n°- Sorex 52 i, 3 r. 22 s. 



Fig. 22.— „ „ 73/, 2 7-. 20 5. 



Fig. 23.— „ „ 73 h, 2, 1 r. 16 s. 



Fig. 24.— „ „ 45 c, 3 »•. 17 s. 



Fig. 25.— „ „ 42 c, 3 n 8 s. 



Fig. 26.— „ „ 51/, 4 r. 15 s. 



Pigs. 27 and 27 «. — The same, with the allantoidean trophoblast applied 

 against the uterine wall and the trophoblastic protuberances, k., fitting into 

 the secondary epithelial crypts, ep. The specimen from which these figures 

 were taken having been differently preserved from all the others, and the 

 histological details of the proliferated epithelium being less distinct, this 

 region is indicated by a blank space in Tig. 27. There are unmistakable 

 indications of the separation of this trophoblast into a cytoblastic and a plas- 

 modiblastic portion (cf. Fig. 79). 



Fig. 27.— Utr. Mus. Cat. n°- Sorex 106/, 3 r. 12 s. 

 Fig. 27 a— „ „ 106/, 3 r. 4 s. 



Fig. 28. — The same, in a yet later stage. The trophoblastic protuberances, 

 k., adhere firmly iu the epithelial crypts, ef ., the protuberances being partly 

 hollowed out and filled out by incipient i.llantoic villi, vi. Plasmodiblast 

 extends between the darker zone of the cyti blast and the protuberances. 

 Utr. Mus. Cat. n°- Sorex 3 5, 3 r. 17 *. 



PLATE 34. 



Figs. 29—34 X 100. Fig. 35 X l\. Figs. 36—47 natural size. 



Fig. 29. — Fragment of a section through a yet later stage (cf. Fig. 12). 

 The allantoidean trophoblast has already considerably developed ; the cyto- 

 blastic portion of it has been more deeply stained by the picro-carminate. 

 P. Tissue belonging to the maternal epithelial proliferation. T. Tissue be- 

 longing to the trophoblast (cytoblast + plasmodiblast). The sanguiniferous 

 villi of the allantois that penetrate into this have on purpose been entirely 

 omitted in this figure. White spaces in this figure thus indicate where they 

 are situated. Only the lower boundary line of the allantois is indicated, 

 with a few excrescences adhering against the trophoblast and representing 

 incipient new villi (cf. Fig. 30). Comparison with Figs. 12, 81, and 89 will 

 further elucidate this preparation. The difference should be noticed between 

 the extent and situation of the area vasculosa in this and in the next figure 

 (cf. also Figs. 12 and 13). 



Utr. Mus. Cat. n°- Sorex %hg,2r.l1 s. 



Fig. 30.— The same, in a later stage (cf. Figs. 13, 82, and 94). The 

 cytoblastic trophoblast is only here and there visible as a distinct layer out- 

 side the allantoic villi ; generally it cannot be readily distinguished from tlie 



