THE INTESTINES. 



513 



Fig. 209. 



villi (Fig. 208) are so numerous, that when well injected, those whose epi- 

 thelium has be"en detached become colored throughout ; and, in living 

 animals, or those which have 

 just been killed, each villus, if 

 viewed from above, appears as 

 a red dot surrounded by a 

 clear ring. In man, every 

 villus contains a close network 

 of capillaries of 0-003-0-005 

 of a line, with rounded or elon- 

 gated nuclei, which lies imme- 

 diately beneath the homoge- 

 neous external layer of the 

 matrix* and is supplied by one, 

 two, or three small arteries of 



0-01-0-016 of a line. The blood is usually carried back directly into the 

 larger trunks of the submucous tissue, by a vein of 0-022 of a line, 

 which does not arise, as in animals, by the 

 arching round of the artery, but proceeds 

 from the gradual confluence of the finest capil- 

 laries. 



The relations of the lacteals in the villi 

 of man, have not hitherto been perfectly 

 made out; for although the majority of 

 investigators are inclined, like the older ob- 

 servers, to suppose that they commence by 

 one or two csecal branches, yet recently, more 

 and more voices Appear to be raised for the 

 view that they originate in a plexiform man- 

 ner. As to my own opinion, I can affirm no- 

 thing with respect to the human subject, since I 

 have never succeeded in meeting with villi dis- 

 tended with chyle, and in empty ones, I have 

 been unable to obtain any decisive evidence ; 

 on the other hand, in animals, I feel certain 

 that in many cases only a single lacteal, which 

 has a csecal and frequently enlarged end, and 

 whose diameter is much greater than that of 

 the capillaries, traverses the axis of the villus 

 (Fig. 209.) 



FIG. 208. Vessels of a few villi of the Mouse, after one of Gerlach's injections; magni- 

 45 diameters. 



FIQ. 209. Two villi without epithelium and with the lacteal in their interior (from the 

 Calf), magnified 350 diameters, and treated with a dilute solution of caustic soda. 



* [The " basement membrane" of Tocld and Bowman. ED.] 



33 



m 



