Introduction. 5 



matter and energy of living things ' (using the term ' living 

 thing ' in its ordinary acceptation), manifestly rests on Physics 

 and Chemistry, since it involves the application of the laws 

 and principles of these sciences to the special case of living 

 matter, whether plant or animal. Contrary, perhaps, to our 

 first anticipation, we find that the phenomena of Biology, 

 complex and involved as they admittedly are, are generally 

 speaking capable of expression in physical terms, while the 

 changes that take place in the animal or plant organism 

 are found to agree in all important points with those which 

 form the subject of chemical and physical investigations. 

 Even mental or psychological phenomena, although the 

 nature of their connection with the chemical and other 

 changes taking place contemporaneously in the brain, has 

 not yet been determined, are undeniably accompanied by 

 some such change, and cannot be said to be independent 

 of the physical and chemical basis on which the science of 

 Biology, as a whole, is built. The dependence of Biology 

 on Chemistry becomes still more evident when we learn 

 that no constituent of living matter is incapable of being 

 classified among chemical substances ; that, in other words, 

 the substances which enter into the composition of living 

 things are among the commonest constituents of the mine- 

 rals of the earth's crust. 



It is usual to classify such departments of knowledge as 

 Geology, Mineralogy, Botany, Zoology, Anthropology, and 

 Sociology as distinct sciences. They cannot, however^ 

 claim a higher rank than that of sub-sciences, while some of 

 them are merely special departments of the four great 

 sciences already mentioned. 



This discussion regarding the position of Biology in a 

 classification of the sciences leads us, therefore, to the con- 

 clusion that Biology has for its subject the matter and 

 energy of living things, and is, therefore, dependent on the 

 more general sciences of Physics and Chemistry, and itself 

 forms the starting-point for a series of special sub-sciences, 



*B 3 



