OF THE CAPILLARY VESSELS. 267 



cles leading, according to the greater number of modern wri- 

 ters, into the lymphatic vessels only, but according to the 

 anatomists anterior to Haller,and some more modern than him, 

 into the veins only; and according to others, both into the ca- 

 pillary blood-vessels and lymphatics. Prochaska adds to this, 

 among the passages of absorption, the organic porosities of the 

 vessels, which would thus be, at once, the passages of exhala- 

 tion and inhalation. Absorption has also been considered as 

 a purely physical phenomenon, comparable to capillary attrac- 

 tion or imbibition, by adducing in support of it, the absorption 

 which occurs in the dead body. 



The fact is that the passages of inhalation are unknown. 

 They appear to be like those of exhalation, the porosities of 

 the solid and permeable substance of the body. Absorption, 

 however, like secretion, is an organic and vital phenomenon 

 altogether different from imbibition in the dead body, as is de- 

 monstrated by the selection of the substances absorbed, and by 

 the modifications which the activity of absorption presents in 

 various cases. When, in this work, the term absorbents is 

 used, it is to designate by a single word the unknown passages 

 by which foreign substances enter, and those by which the 

 matters of the intrinsic absorptions pass into the circulatory 

 apparatus.* 



394. Imagination has not stopped at the creation of exha- 

 lent and inhalent vessels, of which we have been speaking; 

 nutritive vessels have been also supposed. 



The following are the principal opinions entertained on this 

 subject. Boerhaave and R. Vieussens having admitted colour- 

 less and decreasing vessels, the former conceived the body en- 

 tirely constructed of vessels, even those parts which can not 

 be injected. According to Boerhaave's system, the smallest 

 elementary fibres form minute membranes, rolled upon them- 

 selves, to constitute the smallest nervous vessels. From these 

 smaller vessels result the vascular membranes forming larger 

 vessels, and so on to the largest ones. He also determined 



* See experiments on Edosmose and Exosmose in the No. 7 of the Ameri- 

 can Journal of Med. Sciences. TAAVS. 



