PROCEEDINGS OP THE SOCIETY. 903 



In regard to this I have to say that the acid was removed as well 

 as possible by continued washing with distilled water, before applying 

 the silver reagent. Besides, the alkaline nature of the latter would 

 have neutralized any trace of the acid left. The reason why, after 

 killing with citric acid, no more silver was reduced by the cells, was 

 certainly a chemical change of the protoplasm itself. 



Whoever will take the trouble to study our publication, ' Die 

 Chemische Kraftquelle im lebenden Protoplasma (The Chemical Source 

 of Power in the living Protoplasm), will find that every precaution was 

 taken in all our labours to avoid errors and false conclusions. We 

 have killed the cells in all possible ways : by starvation, by desicca- 

 tion, by heating to 50° C, by mechanical action, by electrical sparks, 

 by ether, alcohol, carbonic acid, kerosene, sulphuretted hydrogen, by 

 sugar, tannin, by acids, alkalies, and salts ; and in all these cases the 

 protoplasm had become changed, so as to be incapable of reducing 

 silver. In one case, however, death was produced by destruction of 

 the structure and organization alone, the chemical nature remaining 

 unchanged ; it was by the action of certain poisons, especially alka- 

 loids. We have described these cases in minute detail in our 

 publication. 



Life must be considered as the result of two functions : — 



1. Of a specific chemical motion — viz. the energy of the aldehydic 

 groups in the molecule of the active albumen. 



2. Of the organization of the protoplasm — viz. the specific mole- 

 cular construction from molecules of active albumen. If one of these 

 functions is destroyed, death is the result (see pp. 25 and 77 of our 

 publication). 



No thinking mind will doubt that the vital force is a mode of 

 motion, like all other forces of nature. We have proved beyond a 

 doubt that the vital force is the result of a specific chemical motion, as 

 minutely explained in our publication (see pp. 19-25 and 88). 



It is true there are many objects which are so sensitive, that they 

 die too quickly to give the silver reaction, which is only slowly 

 developed, requiring many hours ; we have described such cases too 

 (see pp. 60-62 of our publication). 



I have proved, furthermore, that the quantity of reduced silver 

 corresponds with my theory (see pp. 91, 92), and have arranged now to 

 analyze the product formed by the action of the silver solution upon 

 the living protoplasm ; a product that it is impossible to obtain with 

 dead protoplasm. 



In regard to Mr. Stewart's remarks on ' silver-staining,' it is most 

 essential to note that the silver-staining process is based upon the 

 action of light ; many organic substances will reduce silver, if in con- 

 tact with light. Our process, however, goes on in absolute darkness ! 

 and is quite a different thing from the ' silver-staining process.' 



Eecently some volatile aldehydes have been discovered in plants 

 by Mori and by Eeinke ; but we must utterly deny that our observa- 

 tion has anything to do with such an aldehyde. Our objects were 

 entirely free from any volatile or soluble aldehyde ; hence our reaction 

 shows conclusively the aldehydic groups as constituent parts of the 

 molecule of active albumen. The albumen, passing from the active 



