336 PROTEINS 



that during the ripening of pea seeds there was an increase in 

 the amount of the protein at the expense of the amino acids 

 and organic bases, as indicated by nitrogen determinations of 

 these compounds. 



This synthesis is hastened by drying and the presence of free 

 oxygen, which gas, however, has an indirect action. 



The results were not so well marked for all seeds ; thus 

 under similar conditions but little protein synthesis took place 

 in the maize, whilst in the sunflower there was a decomposition 

 of protein. 



Since the hydrolysis of proteins is naturally effected by 

 means of enzymes, the question arises, is the action of these 

 catalysts reversible ? (See p. 363.) 



The problem is the more complicated since substances 

 may be formed in plants which do not occur when proteins 

 are hydrolysed in the test tube. Asparagine is a case in 

 point. This substance is sometimes very abundant in plants, 

 especially in seedlings germinated in the dark,* and if it be a 

 direct stage in the analysis of proteins, then it would appear 

 that the sequence obtaining in the plant is not the same as 

 that which happens in vitro. This, of course, is not im- 

 possible indeed, some would say that it is extremely probable 

 but the opinion is now generally held that asparagine is a 

 secondary product.f Thus it occurs in greater abundance in 

 the developing parts than in the organs where the protein 

 reserves are stored ; Schulze \ found that only 7-62 per cent 

 of asparagine occurred in the cotyledons, whilst 3i'8i per 

 cent obtained in the axis of the lupin. Also the relative 



* This may easily be shown by germinating lupin seeds in the dark until the 

 hypocotyl is a few inches in length. On mounting a section of the hypocotyl in 

 strong alcohol and examining under the microscope, a large number of crystals 

 of asparagine will be seen. 



t Prianischnikow : " Ber. deut. bot. Gesells.," 1904, 22, 35; Schulze: id., 

 1904, 22, 385 ; 1907, 25, 213 ; Zaleski : id., 1906, 24, 292. 



J Schulze: "Landw. Jahrb.," 1878, 411. 



