56 THE SYNTHESIS OF PROTEINS 



the formation of these products, the plant has no choice in the 

 matter, since with given conditions of chlorophyll, carbonic 

 acid, light energy and potassium nitrite the synthesis must 

 follow its natural course just as we have found to take place 

 in vitro. 



" A further conclusion of importance is that the region where 

 the synthesis occurs must necessarily be restricted to the 

 leaves. Since it must not be forgotten that the synthesis of 

 hexoses is taking place concurrently, the conditions are perfect 

 for the formation of glucosides and we believe that the products 

 of the nitrogen synthesis are translocated as soluble glucosides. 

 The fact that nitrogen derivatives are found in other parts of 

 the plant cannot be accepted as an argument that they must 

 have been synthesized in those parts. There can be no doubt 

 that the synthesis takes place in the leaves and that the com- 

 pounds are subsequently distributed as soluble glucosides by 

 the normal translocatory processes." 



Commenting on the last statement, it should be borne in 

 mind that no evidence is adduced in support of the existence of 

 such soluble protein glucosides. 



The authors summarize their ideas in the following scheme. 



Potassium nitrate Carbonic acid 



* * 



Potassium nitrite Activated formaldehyde 



Formhydroxamic acid 



* 



Hexoses 



1 1 



Nitrogen base? a Amino-acids 



* * 



Alkaloids and xanthine I 



derivatives Substituted a-amino-acids 



(Histidine, etc.) 



*. 



Proteins 



Whilst the foregoing pages have dealt with the synthesis of 

 proteins in daylight or ultra-violet light it must be borne in mind 

 that the synthesis of proteins can also take place in the dark 

 and in tissues free from chlorophyll, provided that an adequate 



