PEEFACE. 



" Physiology is to a great extent applied physi<^ and chemistry." 



Peof. Huxley. 



"A true hnomledge of biology must be based on a knowledge qf chemistry 

 and physics." — M. M. P. Mum. 



" Biology being tlie science which deals with the matter and energy of living 

 things, manifestly rests on physics and chemistry, since it involves the appli- 

 cation of the laws and principles of these sciences to the special case of living 

 matter." — E. J. H, Gibson. 



" Chemistry lies at the basis qf physiology," — A. BiNET. 

 " It is impossible that physiology can ever acquire a scientijic foimdation 

 without the aid of chemistry and physics." — J. TON LlEBlo. 



The branch of biology detailed in the following pages has 

 had only a few workers; for the reason that the majority of 

 biologists are not chemists, and consequently have not the 

 necessary - manipulative skill in applying a science like 

 chemistry to the solution of biological problems. 



The true functions of the various organs of the Invertebrata 

 have always been, until recent years, more or less prob- 

 lematical. Morphology and histology alone could not answer 

 correctly the questions involved ;• but physiology with diemical 

 and physical methods of- research have illuminated very 

 many obscure problems concerning the functions of the 

 various organs -and tissues of the Invertebrata < and no doubt 



