326 SMALL INTESTINE — STRUCTURE OF VILLI. [sECT. 152. 



of which the former, in man, not unfrequently contain fat- 



ing. 137. 



Vessels of two of the villi of the mouse, 

 from an injection by Gerlach. Magnified 

 45 times. 



granules, and in pathological cases, 

 brownish or black pigment. The 

 blood-vessels of the villi (fig. 137) 

 are so numerous, that when well 

 injected, those villi which are de- 

 nuded of their epithelium become 

 completely coloured; and in living 

 or recently dead animals, each villus, 

 when viewed from above, appears 

 as a red point surrounded by a 

 clear border. In man, every villus 

 is supplied by one, two, or three 

 small arteries, of o'oi'" to o"Oi6'" in 

 diameter, which form a close netwoi'k 

 of capillaries, o , oo3'" to o - oo5'" wide, with round or elongated 

 Fig. 13s. meshes, situated immediately beneath the homo- 

 geneous outermost layer of the matrix. This net- 

 work mostly conveys its blood directly into the 

 larger trunks of the submucous tissue by means of 

 a vein, o - 022'" in diameter, which does not arise, as 

 in animals, by a reflexion of the artery, but gene- 

 rally by the gradual coalescence of the finest 

 vessels. 



With reference to the relations of the chyle- 

 vessels in the villi, I can affirm with confidence, as 

 to man and many animals, that in- many cases 

 only a single, blind, chyle-trunk, of much larger 

 diameter than the capillaries of the villus, runs in 

 the axis of the latter (fig. 138) ; and I think it 

 probable, that all the narrow villi, especially the 

 cylindrical and filiform, are so circumstanced; 

 whilst in the broad and laminated, two, or even 

 (as Brilehe found in the weasel and rat) three and 

 four such trunks exist. As formerly, so now, I 

 must, with many other authorities, express myself 

 decidedly against the notion of a ramification of 

 the chyle-vessels in the villi', and I believe that 

 epitheiium,Trithtte striated collections of fat in the parenchyma of 

 mtewo^magnineci the villi have been held for chyle-vessels; perhaps, 

 treatedwut'diiiftea also blood-vessels filled with dark granular particles 

 caustosoda. From ( Bruch ^ wllicll Virchow, also, has often observed. 



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