234 DIGESTION. [CHAP. xxv. 



to the ileum, and ought to be regarded as forming a special 

 anatomic-physiological feature of that portion of the intestine, 

 and as indicative of its proper limits. We find in man as many 

 as from seventeen to twenty-two patches, but with great variety 

 both as to number and size. The patches are smallest towards the 

 jejunum, and increase considerably in size towards the ccecum, so 

 that some quite near the latter intestine, measure from two to four 

 inches in their long diameter. 



Each of the small glands, the aggregate of which constitutes the 

 patch of Peyer, is placed in a depression and surrounded by a 

 groove resembling that which surrounds the papilla3 vallatse of the 

 tongue ; some being enclosed by a circle of the orifices of large 

 tubes of Lieberkiihn. It seems to be in every respect similar, as 

 regards its intimate structure, to the solitary glands, and probably 

 discharges its secretion by a similar mechanism. The arrange- 

 ment and structure of these glands are well seen in a vertical sec- 

 tion, as represented by fig. 167. 



Peyer's glands are well developed in the Carnivora, more so than 

 in Herbivora, and they commence very high up in the intestine, 

 whence it would appear that the shortness of the small intestine, 

 which distinguishes the former animals, is due to the imperfect 

 development of the duodenum and of the jejunum. 



The office of these glands is involved in great obscurity ; most 

 probably it is connected with the further reduction of the ali- 

 mentary matters as they pass through the intestine. But we are 

 unable to form any conjecture as to the causes which determine 

 the peculiar shape or position of the glands, or as to the nature of 

 their secretion. They are larger and more developed during the 

 digestive process than during fasting, a fact which denotes that the 

 former is the period of their greatest activity of function. It is not 

 impossible that the peculiar odour of the faeces, which is in a 

 great measure characteristic in particular classes of animals, may 

 be due to a secretion by those glands. 



In typhus or typhoid fever, these and the solitary glands are 

 prone to become inflamed and to ulcerate. The poisonous matter 

 which generates the fever, is apt to fix on these glands; or they 

 may be the special channel for its elimination, and in the process 

 they suffer irritation. In phthisis these same glands are very 

 liable to become the seat of the tubercular deposit, and also of an 

 ulcerative process, whence results the diarrhoea, which proves so 

 troublesome an accompaniment of that disease.* 



* Some excellent remarks on the structure of the solitary and Fever's glands 



