MOLECULAR STRUCTUEE AND LIFE — PTCTET. 205 



camphors, and of tannins, the carbon and oxygen atoms of the 

 anthocyanins, the carbon and nitrogen atoms of chlorophyll and of 

 all the alkaloids, are uniformly joined in closed chains. 



We have seen that it is exactly the reverse with the nutritive sub- 

 stances of the cell. I see plainly in this different disposition of the 

 atoms the reason why the molecules of one group should penetrate 

 the living cell, and why those of another group would be excluded. 

 A straight wire will penetrate a narrow opening if introduced end- 

 wise, but will not pass if made into a ring. Likewise the inter- 

 molecular passages of the cellular walls permit the passage of the 

 flexible strings of open chains while they oppose the entrance of the 

 massive and rigid rings which form the cyclic molecules. 



Moreover the waste products of metabolism are primarily bodies 

 with open chains, like the substances from which they are derived. It 

 is therefore only after an impact that they acquire the cyclic structure 

 which renders them inoffensive. There is here a reaction of the 

 living plant against the toxic substances that it produces, and this 

 reaction consists in a modification of the internal structure of these 

 substances; the plant is defended against these poisons by cyclising 

 them. There are therefore in the vegetal organism two parallel 

 processes of synthesis, one which, reuniting the atoms by simple 

 juxtaposition, forms the long open chains that will result in the 

 formation of the complex molecule of the proteins, the other, carrying 

 on a veritable street inspection, cleans the organism of all the detritus 

 left over from the first synthesis, isolating all particles no longer 

 available for constructive metabolism as well as those thrown off by 

 destructive metabolism. 



This hypothesis, being announced, it remains to verify it by ex- 

 periment and to show how cyclisation operates in the plant. This 

 is what I now proceed to do, at least so far as it applies to the alka- 

 loids. Starting with the idea that, in organic synthesis, the best 

 way to attain the end is to imitate nature, I have always sought in 

 my attempts to artificially reproduce vegetable alkaloids to work 

 under conditions as nearly as possible identical with those of the 

 living plant. This idea has been followed in recent work in my 

 laboratory by MM. Gams, Spengler, Kay, and Malinowski, and by 

 Mile. Finkelstein work has been carried on upon the synthesis of 

 berberine and a number of the alkaloids of opium. 



We have uniformly chosen as the starting point of our operations, 

 on the one hand, such substances as are known to be formed in 

 plants by the decomposition of the proteins, and, on the other hand, 

 compounds, such as formaldehyde, which are derived in part from 

 the carbonic acid of the air. In the condensation of these with each 

 other we obtain certain cyclic alkaloids identical with those pro- 

 duced in vegetable tissues. I have thus succeeded, in collaboration 



