SECT. 152.] SMALL INTESTINE — STRUCTURE OF VILLI. 327 



Besides these parts, the villi, as Brucke recently discovered, 

 contain, more towards the centre around the Fig. 139. 

 lymphatic vessels, a thin layer of longitudinal 

 smooth muscular fibres, with very delicate narrow 

 fibre-cells, which, in favourable cases, are very 

 distinct even in man, and, as I find, are continued 

 down between the Lieberkuhnian glands, and con- 

 nected with the muscular layer of the mucous 

 membrane. They occasion the shortening or con- 

 traction of the villi discovered by Lacauchie, which 

 is very evident immediately after death (fig. 139), 

 and, according to BriicJce, is also perceptible in 

 living creatures, and which very probably exerts an 

 important influence upon the further movement of 

 the chvle and venous blood in the villi, that is, 



, . . .An intestinal 



supposing there is no reason against the assumption viuus of the cat, 



1 , . . . ,.„ , T in the act of con- 



of repeated contractions during lite. JNo nervous traction. Magni- 



elements are known to exist in the villi; but the 



walls of the intestine are rich in nerves, and even contain, as 



Fie. 140. 



A. Two n'ffi, with their epithelium, from the rabbit, magnified 73 times, a. Epithelium ; 

 h. parenchyma of the villus. U. A detached sheet of epithelium, magnified 300 times. 

 <i Membrane raised up by the action of water. C. Single epithelial cells, magnified 350 

 times. <(. with, 6. without, a raised-up membrane ; c. a few cells from the surface. 



