ANATOMY OF THE MUCOUS COAT. 45 



In the stomach, the largest of these follicles is about one- 

 ninety-eighth of an inch in diameter, and the smallest about 

 one-four hundred and ninetieth. In the colon the largest is 

 about one-two hundred and forty-fifth of an inch in diaraeter, 

 and the smallest about one-four hundred and ninetieth. In the 

 small intestines their size varies in about the same ratio as in 

 the colon, but they are much more irregular in shape, being 

 scattered more in groups, in consequence of the villi interve- 

 ning : some of them penetrate obliquely towards the founda- 

 tions of the villi; hence, when examined from the exterior, 

 their distribution is more regular, and they are seen lodged in 

 the cellular coat of the gut. 



I have endeavoured to keep the estimate of the number of 

 follicles below what other calculators would make it upon an 

 observation of my preparations, and a fair measurement of the 

 area of the alimentary canal, lest the number may seem ex- 

 cessive and incredible ; I have, therefore, the most reasonable 

 assurance of being within bounds on that point. I may now 

 ask their use ; is it to secrete or absorb ? If they are simply 

 secernents of mucus, the number, one would think, much 

 greater than so limited a secretion requires moreover, why is 

 it that they become smaller and less numerous towards the 

 lower end of the large intestine, where greater lubrication is 

 required for hardened faeces; in addition, are not the glands of 

 Brunner, (solitaries,) and of Peyer, (agminate*,) amply suffi- 

 cient to furnish the required mucus? Again, after most sedu- 

 lous observations upon the villi of all kinds, finely erected by 

 my injections, and placed under most accurate, simple, and 

 compound microscopes, I find, invariably, a polished reflecting 

 surface, uninterrupted by foramina, either at their ends or 

 sides, while many of these follicles are found passing obliquely 

 into their bases. An excellent Woollaston's doublet, which 

 makes the villi of the ileum appear an inch long, exhibits them 

 with a polished translucent surface, without foramina, except 

 where a villus from accident has been broken, a contingency 

 readily recognised by one in the habit of viewing them. Fi- 

 nally, if the lacteal foramina of Lieberkuhn and others, do re- 

 ally exist, why is it that the raising of the intestinal epidermis, 

 by inflation, does not exhibit these foramina by the air escaping 



