N E W P U B L I C A T I O N . 79 



the upper margin ; but two inches above the upper margin the 

 diameter of the trunk has increased, since the injury, nearly twice 

 as much as that below ; the shape, too, of the upper margin is 

 different from the lower, the former being quite oblique, the latter 

 direct. There is no branch below the wound. 



The third chapter of Prof. Draper, on the chemistry of plants, 

 treats of the circulation of the blood, or rather the mechanical 

 cause of the circulation. In this essay, contrary to the common 

 notions which prevail, the movement of the blood is not due to 

 the action of the heart, or at least it plays quite a subordinate 

 part. What, then, is the power which moves the blood ? Prof. 

 Draper maintains that this power is obtained from the affinity 

 which arterial blood has for carbon. Thus, p. 36, § 114, "The 

 oxygenizing action of the arterial blood is, therefore, the true 

 cause of the systemic circulation." The principle upon which 

 this power is based is, " that if two liquids communicate with one. 

 another in a capillary tube j or in a porous or ■parenchymatous struc- 

 ture^ and have for that tube or structure different chemical affini- 

 ties ^ movement will ensue; that liquid which has the most energetic 

 affinity will move with the greatest velocity, and may even drive 

 the other liquid entirely before it.'''' — p. 35. 



Now for the facts and their application : the arterial blood go- 

 ing from the heart outwards into the parenchyma or cellular struc- 

 tures, contains an excess of oxygen, which it has just received in 

 the lungs ; this oxygen is ready to combine with or burn out any 

 carbon in those structures, hence it moves towards them. When, 

 however, this affinity is satisfied, or when the oxygen is neutralized 

 by carbon, and perhaps by hydrogen, it is prepared to leave these 

 structures. It is then, however, venous blood. Now, as the 

 movement in the arteries is sustained by the affinities of the ox- 

 idized blood, and as it moves towards them, the venous blood is 

 driven before the arterial. W^e will not, however, dwell upon 

 this subject, but refer our readers to the book itself, only we \vish 

 to make two inquiries : first, admitting the chemical affinity which 

 is supposed to exist between oxidized blood and the parenchyma- 

 tous structures, shall we not be obliged to admit also that this affi- 

 nity acts at sensible distances ? and second, how and by what force 

 is the circulation carried on in the lymphatics and lacteals ? 



Passing over those chapters which are devoted to the considera- 



