136 ON THE NATURE AND PRINCIPLES OF 



which connect the two great systems of divergent 

 and convergent blood-vessels. And if we admit the 

 correctness of the prevailing opinion, that all the 

 great functions of the circulation, such as secretion, 

 nutrition, and absorption, arc in some incomprehen- 

 sible manner performed by these highly endowed 

 tubules, and that the contiguous arteries and veins, 

 and, in fact, all the different parts of the circulating 

 system, are provided for the sole purpose of supply- 

 ing them with blood, it may then be convenient to 

 retain this exclusive application of the term, lint 

 both the anatomical and physiological reasons in 

 favour of the maintenance of this distinction would 

 seem to be destroyed by the fact, that in certain 

 tissues of the body some of those functions do pro- 

 ceed, and inflammation and other morbid actions do 

 occur, although no such intermediate cylindrical 

 vessels can be shown to exist. The opinion has, in 

 all probability, arisen from a too hasty application to 

 the whole body of the results furnished by a micro- 

 scopical examination of the blood's course through 

 the lungs, where, for a specific purpose, the extent 

 of the intermediate vessels is greatly increased. And 

 as I am not aware of any satisfactory reasons for 

 supposing that these intermediate vessels possess 

 functions different from those of the contiguous 

 TCUOUS and arterial ramifications ; and as the latter, 

 and more especially the adjacent arterial twigs, arc, 

 equally with the former vessels, the seat of those dis- 

 orders of the circulation which are now about to be 

 considered, I shall use the term "capillary" in its 

 literal sense as synonymous with " minute." 



