234 Science Religion and Reality 



on that indefinite basis, but in 1897 Atwater and Rosa constructed 

 a large and exceedingly delicate calorimeter by the aid of which 

 they were enabled to determine the total amount of energy entering 

 an animal or a man and the total amount leaving him. The error 

 was exceedingly small and their result was that the amount taken 

 in was exactly balanced by the amount going out. Ex nihilo nihil 

 fit. And this under all conditions. Accordingly not only was it 

 found that the chemical compounds of which the body is made up 

 were all such as could be studied and synthesised in the laboratory, 

 but also there was no doubt that the law of the conservation of 

 energy held as rigidly for the animal body as it did for inorganic 

 nature. Energy cannot arise out of nothing, nor be dissipated into 

 nothing. The organism agrees to this by not keeping any, and by 

 not producing any. 



These, indeed, were the most important of the experimental 

 researches which contributed to the view that mechanistic ex- 

 planations of animal activity were the correct ones, but there were 

 a thousand others which pointed in the same direction. In more 

 recent times the work of Loeb on animal tropisms, which has pro- 

 vided us with a mechanistic theory of the actions of the lower 

 organisms, the researches of Barcroft and Henderson, which have 

 shown the intricate physico-chemical mechanisms in the blood 

 which tend to keep the internal environment of the organism con- 

 stant, and the work of Lillie on fertilisation, all point in the same 

 direction ; all implicitly disprove the contentions of the vitalists. 

 One might continue elaborating the biochemical history of the 

 nineteenth century to great lengths ; one aspect more shall be 

 described. In 181 2 Legallois located the respiratory centre in 

 the spinal medulla, and much was said at the time about the 

 " vital tripod," the heart, the lungs, and the brain. The anima 

 sensitiiia was thus beginning to disintegrate once more. When 

 Schleiden and Schwann, ten years afterwards, discovered the cellular 

 nature of living matter and it was realised that the cell and not the 

 organ is the atom of biology, the anima sensitiva suffered another 

 dismemberment, for it became necessary to allot a vital force to each 

 cell, because single cells might outlast the death of the whole body 

 for a very long time. 



But possibly because of the nature of thought itself, the 

 mechanistic viewpoint was not to be allowed to suppress all other 

 conceptions. There had always, even in the crests of the move- 



