68 INTRODUCTION. 



Thus it is that in the lore of the zoologist and the botanist we may 

 find the key to obscure and important manifestations of aberrant cell 

 life. It is in truth through the pursuit of Comparative Pathology that 

 some of our greatest advances in the conceptions of disease have been 

 won, and in it lies the brightest promise for the future. In the light of 

 embryology many obscure pathological processes become plain and many 

 clews to fruitful research are secured. 



Furthermore, so much depends upon the metabolism of the body in 

 health and disease that it is to chemistry, both physiological and patho- 

 logical, that the scientific physician looks most eagerly for the solution 

 of problems which each day become more numerous and urgent. 



Finally, we are daily realizing more clearly that in those complex 

 and subtle processes which we are wont to call vital, such physical fac- 

 tors as molecular constitution, osmosis and diffusion, gravitation, elas- 

 ticity and pressure are of the highest significance and cannot in our 

 studies be wisely ignored. 



