THE MANIFESTATIONS OF LIFE. 85 



We cannot, therefore, in the present state of knowl- 

 edge pretend to follow the elaborate synthesis of living 

 matter. We can, however, analyze that matter and 

 discover the elementary substances of which it is com- 

 posed, and this has been done again and again with 

 interesting and important results. 



Thus an analysis of vegetable cells shows them, with- 

 out exception, to be composed of C, O, H, N, S, P, K, 

 Ca, Mg, and Fe, while similar analyses of animal cells 

 yield C, O, H, N, S, P, K, Ca, Mg, and Fe, found in the 

 vegetable cells, and in addition Na, Cl, I, and Si. 



It would, therefore, seem that vegetable life is less 

 complicated than animal life, and also that it is more 

 easily carried on. 



It must not be supposed that the elements mentioned 

 comprise the full list of all that may be found in either 

 vegetable or animal tissues; instead they form the 

 indispensable list to which others may be or commonly 

 are added with advantageous results to the particular 

 organisms. Thus, for example, Si is not enumerated 

 among the vegetable components, yet it is frequently 

 present and benefits a plant by increasing the rigidity 

 of its tissues. 



If living substances, either animal or vegetable, re- 

 quire at least ten elementary substances for the elabora- 

 tion of their tissues, it is evident that they cannot per- 

 form their vital functions when the supply of these 

 elements fails. 



It is also evident that no substance can be so well 

 adapted for the supply of the essential elements, in the 

 most useful combinations, as living substance itself, which 

 explains why living beings of the highest kind so uni- 

 versally live upon living things of other kinds. The 

 next most useful material would be that which had 

 been living, but is in process of dissolution into similar 

 compounds of still assimilable quality. 



It is, however, evident that primordial forms of life 

 could neither feed upon antecedent life or its derivatives, 



