THE BREATH OF LIFE 



upon the individuals of another species; the kidney 

 of a cat, for instance, cannot be substituted for 

 that of a dog, although the functions and the anat- 

 omy of the two are identical. It is suggested that 

 an element of felineness and an element of canine- 

 ness adhere in the cells of each, and the two are 

 antagonistic. This specific quality, or selfness, of 

 an animal pervades every drop of its blood, so that 

 the blood relationship of the different forms may 

 be thus tested, where chemistry is incompetent to 

 show agreement or antagonism. The reactions of 

 life are surer and more subtle than those of chemis- 

 try. Thus the blood relationship between birds 

 and reptiles is clearly shown, as is the relationship 

 of man and the chimpanzee and the orang-outang. 

 The same general fact holds true in the vegetable 

 world. You cannot graft the apple upon the oak, 

 or the plum upon the elm. It seems as if there were 

 the quality of oakness and the quality of appleness, 

 and they would not mix. 



The same thing holds among different chemical 

 compounds. Substances which have precisely the 

 same chemical formulae (called isomers) have prop- 

 erties as widely apart as alcohol and ether. 



If chemistry is powerless to trace the relation- 

 ship between different forms of life, is it not highly 

 improbable that the secret of life itself is in the 

 keeping of chemistry? 



Analytical science has reached the end of its 



232 



