102 GENERAL PHYSIOLOGY 



here find there in the living organism are met with everywhere in 

 rocks in the form of their oxides, sulphur compounds, and various 

 salts. 



This survey shows that all organic elements help at the same 

 time to constitute the inorganic portion of the earth's surface. 

 Since, moreover, chemical analysis of living substance has shown 

 that no constituents but these organic elements are to be found 

 in the organism, the important fact follows that an elementary 

 vital substance exists no more than a specific vital force. The 

 conceptions of a " vital ether,'' a " spirihis animalis" a " vital 

 matter," etc., with which the earlier physiology so freely dealt, 

 have, therefore, in harmony with the advanced development which 

 analytical chemistry has undergone at the present time, com- 

 pletely disappeared from the present theory of life; living 

 substance is composed of no different chemical materials from 

 those occurring within lifeless bodies. 



Nevertheless, one fact deserves mention, viz., that the few general 

 organic elements are not scattered irregularly here and there 

 through the natural system of elements, but they occupy a definite 

 position, being remarkable as elements having very low atomic 

 weights. Hence the conclusion may with great probability be 

 drawn that in the evolution of the elements the organic elements 

 arose by condensation very early, and therefore existed in the very 

 early stages of the development of our planetary system, at a time 

 when other elements, such as the heavy }netals, had not yet been 

 formed. 



2. The Chemical Compounds of the Cell 



Living substance must be killed before its chemical composition 

 can be learned. Paradoxical as this may sound, at present it is 

 the only way by which a knowledge of the chemistry of living sub- 

 stance can be obtained. The biting sarcasm that Mephistopheles 

 pours out before the scholar upon this practice of physiological 

 chemistry must be quietly endured. It is not possible to apply 

 the methods of chemistry to living substance without killing it. 

 Every chemical reagent that comes in contact with it disturbs it 

 and changes it, and what is left for investigation is no longer 

 living substance, but a corpse — a substance that has wholly 

 different properties. Hence ideas upon the chemistry of the 

 living object can be obtained only by deductions from chemical 

 discoveries in the dead object, deductions the correctness of which 

 can be proved experimentally in the living object only in rare 

 cases. This alone is responsible for the excessively slow advance 

 of the knowledge of the chemistry of the vital process. It is evident 

 that the greatest foresight is necessary in applying results obtained 

 upon the dead object to conditions in the living, and it must con- 



