WilHam A. Hilton 481 



for some time, later they grow downward and at about three weeks 

 after birth they have the characteristic appearance of long, narrow 

 crypts and appear like continuations of the bases of the villi in the 

 submucosa (Fig, 87). 



The development of the crypts in the large intestine is much more 

 clearly seen in some cases, because as development proceeds fewer new 

 villi are formed than is the case in the small intestine. The develop- 

 ment of the crypts in the large intestine was found to be similar to 

 those farther cephalad, but apparently we have a sort of compensatory 

 development as follows : In the small intestine few glands are developed 

 between the primordial villi, but as the intestine proceeds with develop- 

 ment new villi (such as Fig. 57) are developed between the already 

 formed villi and glands, but in the large intestine after the first villi 

 are developed, there are very few formed from buds, as in the case of 

 the small intestine, and to take the place of such a formation many 

 more crypts are developed than is the Qase in the small intestine. 



So far as my observations go all these intestinal glands develop by 

 a downgrowth of the epithelial surface, similar to that described by 

 KoUmann, 98, and Voigt, 99. 



In some cases a crypt may be seen to start at the edge of a villus 

 base, but careful study has convinced me that without doubt the 

 apparent relation of villus and crypt is only apparent, and one may 

 see that in order to have glands composed of bases of villi, it would be 

 necessary to have villi on all sides of a crypt, which is clearly not the 

 case; not only do villi occur which are not near any cr^'^pts, but crypts 

 occur which are not near any villi, as can be seen upon looking down 

 upon a bit of mucous membrane from the intestine of a young animal 

 in which some crypts may be easily recognized as well as some others 

 which are just making their appearance (Fig. 81). Such a view shows 

 the young and older crypts very small as compared with the villi and 

 they appear as little circular dark-staining areas scattered irregularly 

 over the mucous membrane. Comparatively few at an early stage are 

 near villi; later as more glands and villi develop it more often happens 

 that we find villi and glands very near each other. 



In early stages Patzelt and Voigt recognized the anlages of the 

 Lieberkiihnen crypts as little thickened areas of cells between the villi; 

 these areas take a deeper stain and so may be recognized. In white 

 rat these are difficult to observe because they do not stain much more 

 deeply than other parts of the epithelium, but after careful observation 

 these beginning crypts may be recognized first by slight thickenings, 

 then depressions, which take a little darker stain in. some cases, due 



