536 A. A. W. HUBREOHT. 



aunulus a cell-layer {an'.) descends, that is parallel to the annulus but adherent 

 to the maternal tissue. The hypoblast adhering against the trophoblastic 

 annulus is cut tangeutially in the upper part of the figure. Its continuation 

 along the omphaloidean trophoblast, missing in this section, is again present 

 in the neighbouring sections. 



Utr. Mus. Cat. n°- Sorex 106 a, 3 r. 15 s. 



Fig. Ma. — Pseudo-karyokinetic and other phases of the nuclei of Fig. 84 

 in the region where histolysis is most actively going on. 



Fig. 85. — An allantoidean villus in an early stage ; massive, with a central 

 blood-vessel and peripheral blood-spaces communicating with that central 

 one (cf. Figs. 30, 81, 82, and 86). 



Utr. Mus. Cat. n°- Sorex 130 a, 2 r. 13 *. 



Fig. 86. — The tops of two other allantoidean villi, in a later stage of 

 pregnancy (the embryonic blood-corpuscles are here represented as red discs, 

 the maternal as dots). The tissue of the villus is less compact, the blood- 

 spaces in it are arborescent and partly intracellular. Between the two villi, 

 as well as right and left of them, strands of trophoblastic tissue are pictured, 

 carrying spaces with the so-much smaller maternal blood-corpuscles. It has 

 here already become considerably more difficult to distinguish between the 

 tissue of the villus and of the intervening trophoblast than it was in Figs. 

 81 and 82. On the other hand, it is here not yet quite so difficult as in the 

 still later phases of pregnancy that are represented in Figs. 52 and 53. There 

 is as yet hardly any other tissue between the muscularis and the maternal 

 epithelial proliferation, as far as it is yet preserved (cf. Figs. 13, 14, 15, 

 and 54). 



Utr. Mus. Cat. ir- Sorex 80 a, 3 n 5 «. 



PLATE 39. 

 Figs. 87, 90—92 x 480. Fig. 88 x 100. Figs. 89, 93, 94 x 260. 



Fig. 87. — A portion of Fig. 11 b, more considerably enlarged. In the free 

 space in the middle of the figure an allantoidean villus is going to penetrate. 

 The layer of darker stained nuclei surrounding that space is the deeper 

 (cytoblastic) layer of the trophoblast. Blood already circulates in tropho- 

 blastic spaces. 



Utr. Mus. Cat. n°' Sorex 3 a, 2, 5 r. 22 s. 

 . Fig. 88. — The region of the trophoblastic annulus of Fig. 12, under higher 

 power. Lateral maternal proliferated tissue already considerably resorbed. 

 New epithelium that has originated behind this (cf. Fig. 84) is further 

 developed and conspicuously folded. 



Utr. Mus. Cat. n°' Sorex 85 a, 2 r. 14 s. 



Fig. 89. — Another part of Fig. 12, more considerably enlarged, further to 

 demonstrate the fusion between the proliferated maternal and trophoblastic 



