On muscular Molion. II7 



blood-vessels, ami the differences in their size, or number, 

 as applied to muscles, can only be adaptations to some spe- 

 cial convenience. 



Another prevalent opinion among anaton)ists h, the in- 

 finite extension of vascularity, which is contradicted in a 

 direct manner by comparative researches. The several parts 

 of a quadruped are sensibly more or less vascular, and of 

 different contextures: and, admitting that the varied dia- 

 meter of the blood-vessels disposed in each species of sub- 

 stance, were to be constituted by the gross sensible differ- 

 ences of their larger vessels only j yet, if the ultimate ves- 

 sels were in all cases equally numerous, then the sole re- 

 maining cause of dissimilarity would be in the compactin-j- 

 of the vessels. The vasa vasnrum of the larger trunks fur- 

 nish no reason, excepting that of ii loose analo<ry, for the 

 supposition of vasa vasorum extended without limits. 

 JSIoreover, as the circulating fluids of all animals .ut com- 

 posed of water, which gives them fluiditv, and of animal- 

 Jzed particles of defined configuration and' bulk; it follows, 

 that the vessels through which such fluids are to pass must 

 be of sufficient capacity for the size of the particles, and 

 that smaller vessels could only filtrate v.'ater devoid of such 

 animal particles: a position 'repugnant to all the known 

 facts of the circulation of blood, and the animal oeconomy. 



The capillary arteries, which terminate in the muscular 

 fibre, must be secretory vessels for depositing the muscular 

 matter, the lymphasducls serving to remove the superfluous 

 cxtravasattd watery fluids, and the decaved substances which 

 are unfit for use. 



The lymphfeducts are not so numerous as the blood-ves- 

 sels, and certainly do not extend to every nuiscnlar fibre : 

 they appear to receive their contained fluids from the in, 

 tersticial spaces formed by the reticular or cellular mem- 

 brane, and not from the projecting open ends of lubes, as 

 IS generally represented. This mode of receiving fluids out 

 of a cellular structure, and conveying them into cylindrical 

 vessels, is exemplified in the corpora cavernosa and corpus 

 spongiosum penis, where arterial blood is poured into cel- 

 lular or reticular cavities, and from thence it passes into 

 common veins by the gradual coarctation of the cellular 

 canals. 



In the common green turtle, the lacteal vessels univer- 

 sally arise from the loose cellular membrane, situated be- 

 tween the internal spongy coat of the intestines and the 

 nmseular coat. The cellular structure may be filled from 

 the lactcals, or the lacteals from the cellular cavities. When 

 IJ 3 injecting 



