Prof. Draper on the Circulation of the Blood. 179 



able of all results, the restoration from death by drowning ; 

 in all these and many other such cases we can give the most 

 felicitous explanation. 



The principal facts which I design here to establish are, — 



First. The systemic circulation is due to the de-oxidation of 

 arterial blood. 



Secondly. The pulmonary circulation is due to the oxida- 

 tion of venous blood. 



And, in conclusion, I shall offer some explanatory remarks 

 on the phenomena of the coagulation of the blood, 



Several physiologists have already made an approach to 

 the doctrine which will be developed in this memoir. Among 

 well-informed writers it is conceded that we must look to the 

 relations between the blood and the tissues for the true cause 

 of the circulation. Thus Dr. Alison attributes the effect to a 

 " series of vital attractions and repulsions," created by the 

 operations to which the blood in the capillaries is subservient, 

 an idea which Dr. Carpenter has rendered more explicit, by 

 suggesting that these forces may not be "essentially different 

 from those which are witnessed in Physics and Chemistry " 

 (Carpenter's Human Physiology, vol. ii. p. 417). But these 

 views do not communicate a definite idea of the true mecha- 

 nism of the motion, nor do they exhibit that phenomenon as 

 clearly connected with well-known chemical changes occur- 

 ring in living systems. Should it appear, as I shall endeavour 

 to prove, that the circulation is a necessary result of the al- 

 ternate oxidation and deoxidation of the blood, we exchange 

 at once a loose and ill-defined conception for a precise and 

 definite fact. 



It will be perceived that I speak of the oxidation and de- 

 oxidation of the blood as the great facts to be regarded, and 

 leave out of consideration the spontaneous changes which that 

 fluid itself undergoes; those minor effects which it impresses 

 on the tissues, and those which they reciprocally impress on 

 it. For the blood experiences in the systemic circulation an 

 incessant change, discharging a double function. Its plasma 

 serves for nutrition, its discs tor the production of heat. But 

 whilst the final function of the plasma and discs is different, 

 there is an intimate relationship between them. It is from 

 the plasma that the discs arise, and at its expense they grow. 

 Moreover, the tissues themselves, in their metamorphoses, 

 impress changes on the blood ; the cells of which they are 

 composed have an ephemeral existence, they dissolve, and 

 the circulating fluid removes their remains and forms new 

 ones in their stead. 



I doubt very much whether animals obtain ready-formed 



O 2 



