FORM AND LIFE. 525 



outside of the "being, but which are in their turn destroyed and 

 pass into other conditions unsuitable to life, and in which they are 

 cast out to re-enter the inorganic world, which is enriched through 

 them with ammonia, carbonic acid, and oxygen. We are not ac- 

 quainted with the nature of this movement ; we know only that 

 it exists by comparing what goes in and what goes out, and these 

 with the intermediate term, the living substance itself. We know 

 that it is propagated at the same time in all the tissues and all the 

 organs of the being, offering in each a special modality while 

 retaining always the same fundamental character. 



This movement is fundamental to the tissues of the living be- 

 ing, from the most simple of them, like the substance of the bone, 

 to the most complex, like that of the muscles or the brain. It is 

 always in the living being, whether it is growing, thriving, or 

 declining toward death, or is attainted with different passional, 

 morbid conditions that might affect it. It is always present in 

 the infinite variety of physiological acts of which our life is made 

 up and which all inevitably lead to an impending molecular modi- 

 fication : the sensation of the retina disturbed by a light-ray, the 

 contraction of a muscle, and even thought. In connection with 

 the last, the effort has been made to reach by tortuous ways the 

 nature of the chemical reactions that necessarily accompany all 

 brain work. Whether this is reached or not, it is impossible to 

 conceive the operation of the nervous elements otherwise than as 

 a phenomenon of nutrition that is, as a modification brought 

 about in the molecular movement. 



But we are still unable to penetrate and discover the true na- 

 ture of that inner molecular movement which makes of animated 

 bodies a world apart from the great cosmos. What are the origin 

 and nature of that new energy communicated to inert matter, giv- 

 ing it properties or rather faculties which it had not before, and 

 which are additional to all those with which the chemist and 

 physicist are acquainted ? Let us say, further, that they are 

 added to these without contradicting them, as was believed for 

 a long time when a kind of antagonism was supposed between life 

 and the physico-chemical forces. Life is in no way a triumph 

 over these forces, and they always keep their predominance. 



Vital movement is, after all, only an episodical modality of the 

 universal faculty which simple and compound chemical bodies 

 have of reacting upon one another. It requires for its manifesta- 

 tion, like every other reaction, definite conditions, confined within 

 narrow limits, of pressure, temperature, and light. 



But the thing we are absolutely ignorant of is the real nature 

 of those inner reactions of which we can not in many cases give 

 the rigorous formula and still less define the thermic equivalent ; 

 the generic quality, as it were, of those movements, at once special 



