GLANDS. 393 



It is also probable that further research will disclose the 

 fact that certain of those glands arranged as mucous glands 

 do not all possess precisely the same structure. 



UNILOCULAR GLANDS. 



FOLLICLES. 



Crypts and follicles are inverted, and sometimes tubular 

 prolongations of one variety of mucous membrane termed 

 compound, and to which that of the alimentary canal, the 

 gall bladder, the uterus and the Fallopian tubes belong. 



In the stomach and in the large intestines these follicles 

 are so closely set in the membrane, that from the mutual 

 compression exercised upon each other, they assume a more 

 or less angular figure ; in the small intestines there are fewer 

 follicles in consequence of the great number of villi present 

 in these, and they are not angular, but round. These fol- 

 licles, which, in the small intestines, are called the follicles 

 of Lieburkiihn, are met with under two very different con- 

 ditions; in each of which they present a very distinct ap- 

 pearance, being in the one case, that is, in their perfect state, 

 lined by epithelium, and in the other being destitute of this 

 epithelium. (See Plate I^.Jigs. 1. 6.) 



The epithelium lining the follicles of the alimentary canal, 

 is of the same kind as that which covers the interspaces be- 

 tween the follicles, and is of the conoidal variety. It lines 

 the entire follicle with a beautifully regular layer of united 

 epithelial scales, which are so large that they nearly fill up 

 the cavities of the follicles, a small circular channel only being 

 visible in each ; this is usually occupied by the mucus 

 secreted by the cells, and appears at the mouth of each follicle 

 as a mere depression, surrounded by a circle of radiating 

 epithelial scales. 



To see the epithelium in the follicles of the human stomach, 

 and even to see the follicles in the mucous membrane of this 

 organ at all, requires that it should be examined immediately 

 after death, as the lapse of a few hours is sufficient to allow 



