536 THE POPULAR SCIENCE MONTHLY. 



The living cell is made up of organic and inorganic constitu- 

 ents. It contains carbon, hydrogen, oxygen, nitrogen, sulphur, 

 phosphorus, chlorine, sodium, potassium, calcium, magnesium, 

 fluorine, silicon, and iron. All these are necessary to life. Ab- 

 straction of one of these elements means death to the organization. 



"We have traced life down to the cell. The lowest forms of 

 life, both animal and vegetable, are single cells, and from these 

 single cells, according to the theory of evolution, all life has been 

 produced. But how about the origin of the first cell ? We do 

 not believe in spontaneous generation — that is to say, no case of 

 the spontaneous generation of life from its elements has ever 

 been recorded by man. But we may reason thus : All substances, 

 even the simplest, require certain conditions for their production. 

 The conditions required to produce a living cell must of necessity 

 be extremely complicated. We do not know of such conditions, 

 but for. the sake of argument we may imagine that at some 

 former period of the world's history conditions may have existed 

 favorable to the production of the first life. 



When we seek to define life we uncover a difficult problem. 

 But who can define the steam engine ? There is no satisfactory 

 definition for either. We can merely say that life is the result of 

 the activity of the cells. 



It follows from this that it is useless to seek for a seat of life. 

 The seat of life has been placed in the blood, but this is the nour- 

 ishing fluid ; in the heart, which is merely the pump for the blood ; 

 in the medulla oblongata, but this contains the nervous center for 

 breathing. There 'is no such thing as a seat of life. Life is the 

 result of the activity of all the organs of the body. 



To every living thing there at last must come an end, and in 

 this fact of death the advocates of a " vital force" saw the neces- 

 sity for their theory. But this is explicable in a material man- 

 ner. In life, as in death, decompositions are continually going on. 

 These decompositions are in kind not different, only during life 

 the products of decomposition are removed, and at death these 

 products remain in the body and poison the individual cells — that 

 is, so alter them that their conditions no longer fulfill the require- 

 ments of life. 



The uneducated Indian when first shown a watch thought that 

 it was alive ; we, on the contrary, have come to regard the living 

 organization as a machine. Upon this basis alone can physiology 

 endure as a science, and physiology is, as the reader knows, noth- 

 ing but the study of the phenomena of life. 



I have endeavored, up to this point, to give an exposition of 

 the material view of life as complete as the most exacting mate- 

 rialist could desire. Many men reach this point and refuse to see 

 further; they make materialism their creed, and cast religion to 



