516 A. A. W. HUBEECHT. 



thus considerably more numerous than the mouths. Between 

 the high and massive epithelium of two neighbouring crypts 

 there is everywhere a core of connective tissue with capillaries, 

 the latter with a flattened endothelium. Especially close to the 

 surface of the mucosa many of these blood-spaces are disposed 

 parallel to that surface, some of them immediately below the 

 epithelium. 



In fig. 74 it can be easily seen that the character of the 

 tissue between the crypts is not that of ordinary connective 

 tissue, nor that the endothelium referred to is as yet very 

 much flattened. The tissue is in a state of most active pro- 

 liferation, and the resemblance to the proliferating epithelium 

 is very close. In the stages of figs. 26, 28, 29, 30, the epithe- 

 lial character comes yet more into the foreground, because the 

 tissue between the crypts is now reduced to actual capillary 

 vessels, taking their course strictly radially. In this stage 

 the endothelium is really flattened (fig. 82), and the radial 

 capillaries are on all sides supported by cryptal epithelial 

 cells. 



The moment the adhesion of the trophoblast has come about 

 the maternal epithelium disappears. Whether it partly dis- 

 integrates in its place, or whether it is actively absorbed by the 

 outer layer of trophoblast cells, cannot be decided with abso- 

 lute certainty ; perhaps both processes contribute, and the 

 phenomenon is readily comparable to what was noticed in the 

 omphaloidean region and represented in fig. 83. 



In fig. 75 the maternal epithelium is yet seen to the right 

 of the trophoblastic knob ; to the left of this it is disintegrat- 

 ing between the darker stained outer trophoblast layer and 

 the sanguiuiferous deeper layer. In the same way the mater- 

 nal cryptal epithelium disappears wherever a trophoblastic 

 knob penetrates into a crypt; in this case the preparations 

 countenance the view that active destruction and absorption of 

 the maternal cells by the trophoblastic ones takes place (fig. 80). 

 As a rule the nuclei belonging to the trophoblast are smaller 

 than those of the maternal proliferation, although this is of 

 course no rigorous means of distinction (cf. figs. 82 and 89). 



