5(5 CARBON IS ACCUMULATED 



blood ; out of the newly-formed blood those parts of 

 organs which have undergone metamorphoses are repro- 

 duced. The carbon and nitrogen of the food thus 

 become constituent parts of organs. 



Exactly as much carbon and nitrogen is supplied to 

 the organs by the blood, that is, ultimately, by the food, 

 as they have lost by the transformations attending the 

 exercise of their functions. 



What, then, it may be asked, becomes of the new 

 compounds produced by the transformations of the 

 organs, of the muscles, of the membranes and cellular 

 tissue, of the nerves, and brain ? 



These new compounds cannot, owing to their solu- 

 bility, remain in the situation where they are formed, 

 for a well-known force, namely, the circulation of the 

 blood, opposes itself to this. 



By the expansion of the heart, an organ in which 

 two systems of tubes meet, which are ramified in a 

 most minute network of vessels through all parts of the 

 body, there is produced a vacuum, the immediate effect 

 of which is, that all fluids which can penetrate into 

 these vessels are urged with great force towards one 

 side of the heart by the external pressure of the atmo- 

 sphere. This motion is powerfully assisted by the con- 

 traction of the heart, alternating with its expansion, and 

 caused by a force independent of the atmospheric 

 pressure. 



In a word, the heart is a forcing pump, which sends 

 arterial blood into all parts of the body ; and also a 

 suction pump, by means of which all fluids of whatever 



