ii SECONDARY DISSOCIATION-PRODUCTS 105 



they give rise to ammo-acids. As plants do not possess a circulatory 

 system comparable to that of animals, the amino-acids remain in situ, 

 i.e. either in the seed or in the cotyledons. Schulze has pointed out 

 especially that the amounts of the amino-acids which are formed 

 during germination agree with the amounts he was able to obtain by 

 acting on the stored reserve-material with acids. He found leucin, 

 amino-valerianic acid, phenylalanin and tyrosin, aspartic and glutaminic 

 acids, lysin, histidin, arginin, guanidin, and ammonia. 



Aspartic and glutaminic acids occur in the largest amounts, and 

 these seem to take the place of one another in different plants, so that 

 in some, even closely related, species one is present in large excess 

 over the other. There occurs in plants, further, a synthesis brought 

 about in this way : A part of the ammonia of the mono-amino-acids 

 is split off and then used for the conversion of some other mono-amino- 

 acids into di-amino-acids. Thus aspartic and glutaminic acids are 

 converted into asparagin and glutamin. 



Aspartic acid, CO . OH . CH 2 . CH(NH 2 )COOH, 



becomes CO(NH 2 ) . CH 2 . CH(NH 2 )COOH, Asparagin. 



Glutaminic acid, CO . OH . CH 2 . CH 2 . CH(NH 2 ) . COOH, 



becomes CO(NH 2 ) . CH 2 . CH 2 . CH(NH 2 ) . COOH, Glutamin. 



Both are found as reserve material in germinating seeds, and may 

 also be transported during germination. Through further complex 

 syntheses they are then built up into albumin, taking up during this 

 process also non-nitrogenous radicals derived from the ever-present 

 carbohydrates, and perhaps also from the desaminated remainders of 

 the mono-amino-acids. Corresponding processes take place also in 

 other parts of the plant. The great importance of asparagin for the 

 albumin-synthesis in plants is also shown by the results which Nageli 

 and Kiihne l obtained with bacteria, as these can grow in media which 

 contain no other nitrogenous substance beside asparagin. 



Only in some conifers does arginin take the place of importance 

 over asparagin and glutamin. 2 Arginin may be obtained in large 

 quantities by boiling coniferous seeds, 3 and is therefore also a primary 

 dissociation-product. 



The fact that individual amino- and di-amino-acids are met with in 

 very varying amounts can only partly be attributed to differences 

 existing in the chemical constitution of the albumins from which they 



1 W. Kiihne, Zeitschr.f. Biol. 29. 1 (1892), 3O. 221 (1894). 



- E. Schulze, Zeitschr.f. physiol. Chem. 22. 435 (1896). 



3 E. Schulze, ibid. 24. 276 (1897). 



