MUCOUS MEMBRANE OF THE SMALL INTESTINE. 319 



rounding structures will admit of these vessels being filled 

 with injection. 



~No satisfactory account has ever been given of nerves in 

 the intestinal villi. If any exist in these structures, they 

 probably are derived from the sympathetic system, which 

 is largely distributed to the intestinal canal. 



The solitary glands or follicles and the patches of Peyer, 1 

 or agminated glands, have one and the same structure ; the 

 only difference being that those called solitary are scattered 

 singly in very variable numbers throughout the small and 

 large intestine, while the agminated glands consist of num- 

 bers of these follicles collected into patches of different sizes. 

 These patches are generally found in the ileum. The number 

 of the solitary glands is so variable that it is impossible to give 

 any general estimate of it. They are sometimes absent. The 

 patches of Peyer are always situated in that portion of the 

 intestine opposite the attachment of the mesentery. They 

 are likewise variable in number, and are irregular in size. 

 They are usually irregularly oval in form, and measure from 

 half an inch to an inch and a half in length, by three- 

 fourths of an inch in breadth. Sometimes they are three or 

 four inches long, but the largest are always found in the 

 lower part of the ileum. Their number is about twenty, and 

 they are usually confined to the ileum ; but when they are 

 very numerous for they sometimes exist to the number of 

 sixty or eighty they may be found in the jejunum, or even 

 in the duodenum. 



Two varieties of these patches have been lately described 



1 These patches, or collections of closed follicles in the intestine are generally 

 called the patches or glands of Peyer, after the anatomist who described them, in 

 1677. It is admitted that Peyer was not their discoverer, as they had been ob- 

 served by Severin, Wepfer, and particularly by Grew, an English anatomist, in 

 1676 ; but the description by Peyer was so much more accurate and- satisfactory 

 than the observations of his predecessors, that the glands have since been 

 called by his name. The work of Peyer is reprinted in the Bibliothcca Anato- 

 mica, by Clericus and Mangetus, tomus i., p. 150. This is entitled, Exertitatio 

 Analomico-Medica Prima, de Grlandulis Intestinorum adjecta, est Anatome Venfri- 

 culi Gallinacei. 



