272 Dr. A. P. W. Philip on the 



fective supply of fluids. In the stomach they were often as 

 copious, sometimes more copious, than usual ; and the latter 

 was almost always the case in the lungs. The fault seemed to 

 be, that a due change on them had not been effected. We know 

 that the vessels of circulation possess no powers but the elastic 

 and the muscular, or what in many of its properties resembles 

 the latter. Can we suppose, that the vessels of secretion, which 

 are only a continuation of those of circulation, all at once 

 assume a different nature ; or is it at all consistent with our 

 knowledge of the phenomena of chemistry to suppose, that by 

 any influence the powers just mentioned, or indeed any that 

 can be supposed to belong to vessels, could be enabled to sepa- 

 rate and re-combine the elementary parts of the blood ? The 

 first of the above positions being set aside, it seems a necessary 

 inference from the experiments referred to, that in the function 

 of secretion, the vessels only convey the fluids to be operated 

 upon by the influence of the nervous system. 



It is not to be overlooked, however, that the vessels convey 

 the fluids in a peculiar way. By the lessening capacities of 

 the capillaries, the blood is divided, as by a fine strainer, some 

 of its parts being too gross to enter the smaller vessels. How 

 far the blood may thus be subdivided we cannot tell. As this 

 structure of the vessels is uniform, we have reason to believe, 

 that its effect on the blood is necessary to prepare it for the 

 due action of the nervous influence. 



We are now prepared to consider the question, for what pur- 

 pose is the influence of the whole nervous system bestowed on 

 the muscles of involuntary motion ? Admitting, it may be said, 

 that the due performance of secretion requires the united power 

 of all parts of the brain and spinal marrow, and that we may 

 therefore explain why their united influence is bestowed on 

 secreting surfaces ; the question still remains, why should their 

 united influence be bestowed also on the muscles of involuntary 

 motion? 



It is evident, that affections of the nervous system could 

 produce no occasional increase of the secretions, were not the 

 sanguiferous system, and particularly the vessels of secretion. 



