4.02 A. A. W. HUBRECHT. 
which blood remains circulating up to the moment of parturition. (Mus. Utr. 
Cat. n° 206¢, 27. 58.) 
Fie. 47.—Part of the boundary region between the compact decidua (D.) in 
the stage of Fig. 44 and the layer of deciduofracts (df). In the protoplasm 
of the latter remnants of (decidual?) nuclei are detected. A small vessel (v.) 
in the decidua opens out in the space between the deciduofracts. (Mus. Utr. 
Cat. n® Hrin. 158 a, s. ult.) 
PLATE XXV. 
Fic. 48.—A section through the region of the omphaloidean trophosphere, 
which is thinning out and becoming membranaceous simultaneously with the 
decidua reflexa. The stage is intermediate between that of Fig. 44 and of 
Fig. 45. Letters as in Figs. 44 aud 45. (Mus. Utr. Cat. Hrin. n°. 94, 4s.) 
Fic. 49.—Section through the region where the uterus lumen gradually 
stretches behind the placentary region preparatory to parturition and the 
shedding of the after-birth. D. The compact decidual tissue. g/. Remnants 
of the coiled ends of glands (?). e. The newly-formed epithelium coating the 
lumen (/), and to the right of the figure passing on to the outer surface of the 
decidua reflexa, or its continuation. This latter portion of the new epithelium 
is shed with the after-birth. Diagrams 35 and 36 should be consulted. (Mus. 
Utr. Cat. n® Erin. 58 4, 6s.) 
Fie. 50.—A blood-vessel with concentrically arranged perivascular decidual 
cells, as it is encountered very coustantly in the decidua during the later 
stages of pregnancy. Between the inner endothelium and the concentric layers 
there is a hyaline membrane, which also contains nuclei. (Mus. Utr. Cat. n* 
Erin. 206, 11 s.) 
Fics. 51—57 give the consecutive phases of the gradual formation of the 
allantoidean diplotrophoblast and thus illustrate the ontogeny of the 
hedgehog’s placenta (already indicated in diagrams 38—36) in fuller histolo- 
gical detail. 
Fig. 51.—This stage, corresponding to diagram 32, may also be compared 
to Fig. 20a, than which it is, however, considerably further developed. 
Tr. Trophoblast with villi (ef. Figs. 42 and 43); the trophospongia is 
left out in this figure. #, Pv., C. and hy. Respectively the epiblast, 
mesoblastic somite (protovertebra), ccelome, and hypoblast of the 
embryo. amn.cav. The cavity above the embryo which is going to be 
converted into the closed amnion cavity. #. am. The sheet of epiblast 
by which from the beginning the embryonic epiblast was attached to 
the trophoblast, and which is now travelling and stretching upwards, 
preparatory to the completion of the amnion, of which it will form the 
inner epiblastic lining. m.som. The mesoblast of the outer half of 
the amnion fold becoming applied against the trophoblast, and forming 
