PREFACE. 



" Physiology is to a great extent applied physics and chemistry" 



PiiOF, Huxley. 



"^ true knowledge of biology must he based on a Jcnoivledge oj chemistry 

 ami physics." — M. M. P. MiiK. 



'^Biology being the science lohich deals ivith the matter and energy of living 

 things, manifestly rests on i)hysics and chemistry, since it involves the appli' 

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

 matter." — K. J. H. Gibson. 



" Chemistry lies at the basis of physiology,'' — A. Binet. 

 " It is impossible that physiology can ever acquire a scientific foundation 

 without the aid of chemistry and physics." — J. von Liebig. 



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 chemical 

 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 



