40 BORDER LINES OF KNOWLEDGE 



tioned. Nothing proves that oxygen combines (in the 

 system) with hydrogen and carbon in particular, rather 

 than with sulphur and azote. Such is the well-grounded 

 statement of Robin and Verdeil. " It is very probable 

 that animal heat is entirely produced hy the chemical 

 actions which take place in the organism^ but the phe- 

 nomenon is too complex to admit of our calculating it 

 according to the quality of oxygen consumed." These 

 last are the words of Regnault, as cited by Mr. Lewes, 

 whose intelligent discussion of this and many of the 

 most interesting physiological problems I strongly rec- 

 ommend to your attention. 



This single illustration covers a wider ground th-an 

 the special function to which it belongs. We are learn- 

 ing that the chemistry of the body must be studied, not 

 simply by its ingesta and egesta, but that there is a 

 long intermediate series of changes which must be in- 

 vestigated in their own light, under their own special 

 conditions. The expression " sum of vital unities " 

 apphes to the chemical actions, as well as to other 

 actions locahzed in special parts ; and when the dis- 

 tinguished chemists whom I have just cited entitle 

 their work a treatise on the immediate principles of the 

 body, they only indicate the nature of that profound 

 and subtile analysis which must take the place of all 

 hasty generalizations founded on a comparison of the 

 food with residual products. 



I will only call your attention to the fact, that the 

 exceptional phenomenon of the laboratory is the pre- 



