ANIMAL AND VEGETABLE 85 



" The act of birth, therefore, brings with it the power 

 to use a mechanism by means of which the oxygen of the 

 air can be used by the body. From that moment the whole 

 of the latent mechanism is in working activity and the 

 individual life is complete. 



" Here we are at one with known facts. Let us now 

 examine the electrical problem in this light. We have seen 

 that we require (1) a source of energy, and (2) an organ to 

 act as generator ; i.e., an instrument or apparatus which, 

 when supplied with material, will generate force. 



" We have found the source in oxygen, and the organ 

 in the body to use it ; let us see whether it is possible to 

 carry this analogy further. 



" In the lung the state of things is air vesicle and 

 capillaries, the interchange between blood and air being 

 oxygen from the air to the blood to enter into combina- 

 tion with the haemoglobin (an iron-containing substance), 

 and CO 2 from the venous capillaries going outwards to 

 air. 



" Now, any change between air and blood must take 

 place through the wall of the capillaries, and the physio- 

 logical fact of the permeability of membranes at once 

 arises. Professor Bayliss' Physiology, and I think, quoting 

 from memory, that the work on this subject has chiefly 

 been done by Professor Sherrington, states that the 

 absorption by colloid surfaces depends on the electrical 

 sign of the surfaces and the substance absorbed, and is 

 more an electrical than a chemical action. Also the experi- 

 ments on permeability of membranes depend on electrical 

 balance and the attraction and repulsion of electro-positive 

 and electro-negative ions, and is again a matter of electrical 

 rather than of chemical activity ; although it would, 

 perhaps, be better to say that chemical action follows the 

 electrical or ionic movement. 



" Having found one possible source of energy, one 



