MOLECULAR FORCES. 167 



organism. Even now a Graham is devoting his energies to the 

 elucidation of the numerous effects of diffusion, and we scarcely 

 yet possess any solid basis for our views of the phenomena which 

 are termed endosmotic. Yet, notwithstanding this great deficiency 

 in our knowledge, the few certain conclusions which we have drawn 

 from our experiments on diffusion and endosmosis have already 

 largely augmented our knowledge of many of the processes in 

 animal life. Our insight into the movements of matter is daily 

 being enlarged by numerous contributions from able physicists, 

 who have elucidated many points which had previously been 

 enveloped in obscurity, and which, without such elucidation, might 

 with equal propriety have been referred to either a vital or to any 

 physical force. Such labours are daily supplying us with the 

 compass and the quadrants by which we may safely steer our 

 course across the vast sea of vital phenomena, and learn the 

 position and reciprocal bearing of each individual point. It will 

 be better, therefore, to wait patiently for the advent of the new 

 discoveries promised to us by these researches, instead of selecting 

 as our guide the mysterious vital force which does not even 

 interpret to our own satisfaction the phenomena we desire to 

 elucidate, but merely plunges us lower into those conflicting depths 

 of physical inquiry in which so many bold adventurers have 

 been already lost. In plain words, it would be far more conducive 

 to the advancement of science, were we to direct our efforts to the 

 task of referring vital phenomena to mechanical conditions, instead 

 of resigning ourselves to the fiction of a general principle, which 

 will never satisfy that natural striving of the human mind which 

 seeks to embrace all phenomena in one ideal connection. 



The living body itself is not the place where we should seek to 

 investigate the forces by which the movements of animal matter 

 are controlled, and it is only when examined externally to the 

 organism that we can make them subservient to the elucidation 

 of the phenomena of life. This is the course which has been 

 pursued by physiologists of recent times, to whose researches we 

 owe a very considerable number of the most interesting conclu- 

 sions regarding molecular motions. When the scalpel of the 

 anatomist has brought to view the delicate structure of all organic 

 parts, and the mode of arrangement and the mutual relations 

 of different phenomena have been studied, the physiologist endea- 

 vours to trace the causal connection of facts to definite laws, and 

 seeks to refer the course of phenomena to other forces besides 

 those which appertain exclusively to the internal mechanism of 

 the body. Whilst in former times physical laws were often not 



