STOMACH AND INTESTINE. 



357 



bowel by reflected light, at a place corre- 



very characteristic appearance. * In like 

 manner, the villi in their immedi: 

 bourhood often appear to radiate outwards 



Fig. 269. 



spending to a cluster of agminate follicles, we manner, the villi in their immediate neigh- 

 see that its surface (wliich is raised above 

 the rest of the intestine, but has no very 

 sharp line of demarcation from it) is occu- 

 pied by a number of irregular shallow de- 

 pressions (I), fig. 267.), at tolerably uniform dis- 

 tances from each other. But when inspected 

 by transmitted light, these fossa? are replaced 



Fig. 268. 



- " . '' i >-> \ \ - 



J ' -*, '(-a 443 'v 



**<-.. ,*'".!- - -, 





Agminate follicles as seen by traitsuiitteil light. Mag- 

 nified about 5 diameters. {After Boelim.) 



a, general mucous surface of the ileum ; b, b, opaque 

 grains corresponding to the several follicles. 



by comparatively opaque grains (l>^b,fig. 268.), 

 of about the size of a millet seed ; the aggre- 

 gation of which renders the whole cluster 

 very distinctly visible by this mode of exami- 

 nation. Finally, the cluster may often be 

 recognised externally, from the bulging of the 

 peritoneal coat which it causes in this situa- 

 tion. Indeed, its constituent follicles may 

 sometimes be seen glimmering through the 

 delicate muscular tunic. 



Each such cluster is composed of a number 

 of follicles, varying from twenty or thirty in 

 the smaller, to at least one or two hundred in 

 the larger, specimens. A careful examination of 

 the mucous surface shows that the depressions 

 just mentioned do not lead to any apertures, 

 but are terminated by a smooth surface, the 

 convexity of which somewhat diminishes their 

 own depth. It is only at the margins, and in 

 the intervals, of these fossae, that we find 

 the tubes and villi proper to the small in- 

 testine. And both of these latter structures 

 are somewhat modified. Those tubes which 

 immediately surround each depression have 

 a circular or elliptical arrangement ; so 

 that their orifices generally form a ring 

 of ten to twenty tubes in the fossa 

 (around a, fig. 269.), and thus give rise to a 



Portion of a cluster of agminate follicles. 



a, a, follicles encircled by apertures of the intes- 

 tinal tubes in the form of a ring ; b, short and ob- 

 tuse villi, occupying the intervals of the follicles ; 

 c, apertures of intestinal tubes, opening irregularly 

 in these intervals. 



from a point corresponding to the centre 

 of the fossa. And both they, and those 

 more equidistant to the several follicles, are 

 very different from the villi seen elsewhere : 

 being fewer (b, fig. 269; a, fig. 270.), shorter, 

 of more irregular form, and often confluent 

 at their bases. 



To demonstrate the structure and arrange- 

 ment of the several constituent follicles of the 

 agminate clusters, requires great care, and 

 very delicate manipulation. At the free 

 surface of the mucous membrane, they are 

 extremely difficult to isolate ; both from 

 their great tenuity, and their intimate union 

 to the neighbouring tubes. Hence the best 

 way of gaining access to them is from the 

 outside of the intestine, where they may 

 often be seen through the peritoneal and mus- 

 cular coats. -f- The removal of these tunics 

 brings them directly into view. To this 

 method of examination must be added care- 

 ful section in the vertical and horizontal 

 planes. 



A proper combination of all these methods 

 of investigation reveals the following facts. 

 Each follicle is a shut sac : having a round^n 

 form, but a somewhat conical apex, which is 

 directed towards the surface of the mucous 

 membrane. Their diameter varies from 1 to 

 2 or 3-50ths of an inch. The base of each 

 is in contact with the muscular coat (which is 

 somewhat thinned in this situation) ; and is 

 united to it by an areolar tissue that resembles 

 the ordinary loose sub-mucous texture, in 

 which the follicle is imbedded by the greater 

 part of its bulk. The short apex of the 

 follicle extends upwards between the lower 

 extremities of the intestinal tubes : and, 

 below their middle, it terminates in the 

 immediate neighbourhood of the general 

 mucous surface, which has already been 



* This appearance is somewhat incompatible with 

 that seen in a vertical section. Hence it is perhaps 

 partially due to pressure or over-disteution of the 

 follicle. 



f Especially after bavin? been rendered opaque 

 by soaking in dilute acids, which coagulate their 

 contents. 



A A 3 



