88 PHYSIOLOGY OF THE CIRCULATION. 



ported on that side than on the rest of their 

 circumference. The influence of a free surface, or 

 of a loose structure, in facilitating effusion, is also 

 strikingly exemplified in many of the phenomena of 

 disease, and is clearly refcrrible to the diminished 

 pressure then acting on the exterior of the minute 

 blood-vessels : and, 2ndly, that the different degrees 

 of compression which the blood endures in the capil- 

 laries of different glands will probably exercise 

 considerable influence in modifying the nature of 

 their secretion. 



The capillaries distributed throughout the rest of 

 the body will, at their junction with the minute 

 arteries, assist the latter in the performance of the 

 function of nutrition. The extent to which their 

 share is limited, must, in each organ or structure, be 

 mainly regulated by the relative facilities afforded to 

 the passage of the blood into and from them. But 

 in the following division of this memoir I shall 

 mention some reasons in support of the opinion, that 

 these vessels, more especially their terminating por- 

 tions, are intimately connected with the adjacent 

 venous radicles in the performance of the opposite 

 function of absorption. 



It may by some be considered that the foregoing 

 vie\vs have too great a tendency to withdraw the 

 functions of secretion and nutrition from the sphere 

 of influence of the nervous system. But as it is 

 generally acknowledged that the nerves possess the 

 power of affecting the contractility of the blood- 

 vessels so as to increase or diminish their calibre, 

 and also that of the pores existing in their walls; 



