SYNTHESIS IN THE PLANT 337 



amounts of asparagine and aspartic acid show considerable 

 variation during germination and, in the last stages, the amount 

 of asparagine formed is in a proportion greater than the amount 

 of protein decomposed. 



The significance of asparagine to the plant is not known ; 

 it would not appear to be used up directly for the synthesis of 

 new protein since its amount does not decrease proportionately 

 to the quantity of protein which is built up ; it has been 

 suggested that asparagine is merely an intermediate step in the 

 synthesis of carbohydrates or fats. 



The method of formation of asparagine is uncertain ; am- 

 monia, which is formed during the decomposition of the 

 primary dissociation products of proteins, may be, according 

 to Schulze,* its starting point, and this combines with an 

 amino acid, possibly aspartic acid, according to Prianischkow, 

 to form ammonium aspartate, which by the loss of a molecule 

 of water gives origin to the asparagine. 



Other views regarding protein synthesis have been put 

 forward ; j- but owing to their not being based on well ascer- 

 tained facts, it does not seem profitable to discuss them here. 



Treub J concluded, from his investigations on the distribu- 

 tion, periodic variation in the amount, etc., of cyanogenetic 

 glucosides (see section on glucosides), that hydrocyanic acid 

 is the first recognizable product of nitrogen assimilation and 

 possibly is the first organic nitrogen compound formed, but 

 the conclusions are not convincing. On purely chemical grounds 

 it is not impossible that acetonecyanhydrin CH 3 COHCNCH 3 

 may be a stage in protein synthesis. 



From the foregoing it is obvious that our knowledge of 

 the synthesis of proteins in the plant is in a very unsatisfactory 

 condition ; and this need cause no surprise in view of the enor- 

 mous difficulty of the subject and the extraordinary complexity 

 of the protein molecule. 



SYNTHESIS OF AMINO ACIDS IN THE PLANT. 



With regard to the synthesis of amino acids within the 

 plant, it is of interest to note that in the laboratory Erlenmeyer 



* Loc. cit. See also Treboux: " Ber. deut. hot. Gesells.," 1904, 22, 570. 

 f Loew: " The Energy of Living Protoplasm," London, 1896, and Munich, 

 1899. 



I Treub: " Ann. jard. bot. Buitenzorg," 1895, 13, i, and 1904, 19, 86. 



22 



