MOLECULAR STRUCTURE AND LIFE — PICTET. 209 



life to the matter itself ; it has not, it can not have both living mole- 

 cules and dead molecules. Life requires an organization, which is 

 that of cellular structure, but it remains, in contradistinction to it, 

 outside the domain of strict chemistry. 



It is none the less true that the content of a living cell must differ 

 in its chemical nature from the content of a dead cell. It is entirely 

 from this point of view that the phenomenon of life pertains to my 

 subject. It is therefore from this view point that it remains for me 

 to examine whether the ideas I have presented can be used for its 

 interpretation. 



A living cell, both in its chemical composition and in its morpho- 

 logical structure, is an organism of extraordinary complexity. The 

 protoplasm that it incloses is a mixture of very diverse substances. 

 But if there be set aside on the one hand those substances which are 

 in process of assimilation and on the other those which are the by- 

 products of nutrition, and which are in process of elimination, there 

 remains only the protein or albuminous substances, and these must 

 be considered, if not the essential factor of life, at least the theater 

 of its manifestations. These alone, in fact, possess those two emi- 

 nently vital faculties of building up their molecules within the cell 

 itself and of reacting to the slightest influences of a physical, chemi- 

 cal, or mechanical nature. They are therefore classified among the 

 most reactive organic compounds that we know, and it is their very 

 reactivity which makes them the supporters of vital phenomena. 

 During the life of the cell they are in a state of perpetual transfor- 

 mation, and are found in a state of stable equilibrium only upon the 

 death of the cell ; or, better to say, this death is only the result of the 

 stabilization of the protein molecules. 



Is this stabilization a chemical process, in the sense that it brings 

 about a modification of the molecular structure? To ascertain if 

 such be the case, and what this modification is, it is necessary to 

 know the constitution of both living albumen and dead albumen. 

 Chemistry, however, is totally ignorant, or nearly so, of the consti- 

 tution of living albumen, for chemical methods of investigation at 

 the very outset kill the living cell. The slightest rise in temperature, 

 contact with the solvent, the very powerful effect of even the mildest 

 reactions cause the transformation that needs to be prevented, and 

 the chemist has nothing left but dead albumen. 



It is therefore only dead albumen that chemistry has been able to 

 study. Thanks to the investigations of a host of eminent men of 

 science, we now know, if not in all its details, at least in great part, 

 the constitution of the albumens. It is Imown in particular from the 

 special point of view that occupies our attention, that the extremely 

 complex molecule of these bodies is formed of an assemblage of a 



