THE INTESTINES. 523 



ring digestion from the Peyerian 2^atches, is greater than that in other 

 jjarts of the intestine, although their villi ave fewer and less developed ; 

 on the other hand, we know nothing of the internal relations of these 

 vessels. They would seem to form networks around the separate folli- 

 cles, at least we see that they compass them externally ; but they do 

 not become inserted into, nor enter them, at any rate upon this surface, 

 as their milk-white color would render their detection easy. Although, 

 then, Briicke has recently affirmed the direct communication of the 

 follicles with lymphatics, I must, for these and other reasons (see Mikr. 

 Anat. II. 2, p. 188), at present doubt the fact. 



The solitary follicles [glandulce solitaria') resemble the separate ele- 

 ments of Peyer's patches so closely in size, contents (I have also seen 

 the internal vessels in them), and general structure, ^.^ ^^^ 



that there is no reason for considering them as dis- 





tinct, particularly since the number of the follicles i^ ''^^^w^^  • 

 is subject to ail possible varieties; and since, in v/j^rS'^' '^S'-..-- 

 animals at least, we find Peyer's patches with 2-3- '^fm^r.i'^ '^ "^^ 

 5 follicles. In man, as all writers justly agree, ^^r-. .^^^'■ 

 their number is exceedingly inconstant: sometimes '■\Wi''''Zt^'^r^''A 

 not one can be found, whilst in other cases, the whole - --^^'- - .^^—^ 

 intestine, as far as the margins of the ileo-C£ecal valve, is thickly beset 

 with them, or lastly, they may occur in the ileum and jejunum, but in 

 no very great number. Their entire absence must probably be con- 

 sidered abnormal, since they are constant in newly-born children, being 

 more abundant in \)a.Q jejunum than in the ileum. The miliary vesicles, 

 however, which are often met with in immense quantities in the small 

 intestine and stomach, in catarrhal affections of the alimentary tract, 

 may very probably be entirely or partially pathological, since the occur- 

 rence of such follicles has been demonstrated in other organs also (in 

 the liver, according to Virchow). The solitary follicles have the same 

 sposition as the elements of the patches, only they occur also in the 

 mesenteric border and support villi upon their intestinal surface, which 

 is usually somewhat convex. 



I consider it as quite certain, that the follicles of Peyer's patches 

 have no apertures, but I may here adduce the following facts. 1. In 

 animals examined while fresh, the capsules are invariably closed, as may 

 be very readily seen in the well-developed patches of the Pig, Sheep, 

 Cat, Dog, <S:c., which I particularly recommend for the examination of 

 these organs, because the patches in the human subject have so fre- 

 quently undergone alteration. 2. The appearance of an aperture may 

 proceed from the depression of the mucous membrane over the single 

 follicles, especially when the projecting portion of the wall of the folli- 



FiG. 21G. — A solitary follicle, covered with villi, from the small intestine. After Biilim. 



