CLASSIFICATION OF VEGETABLE PROTEINS 83 



Such preparations of nucleoproteins as have been thus far obtained 

 from vegetable sources can, in the writer's opinion, be considered only 

 as protein nucleates ; and they in no sense represent actual constituents 

 of the vegetable cells, although it is not at all impossible that similar 

 products may exist there. 



The only extensive study of the character of the " nucleoproteins " 

 obtained from plants which has been made since the true character 

 of the nucleic acids has been established and the basic properties of 

 the proteins recognised, was that of Osborne and Campbell (336), who 

 obtained a large number of products from the wheat embryo, which 

 consisted of protein combined with very different proportions of nu- 

 cleic acid. The aqueous extract of the wheat embryo contains a large 

 proportion of nucleic acid which has been isolated in quantity and its 

 composition and properties determined by Osborne and Harris 

 (602). 



The freshly prepared aqueous extract of the embryo-meal is neutral 

 to litmus, alkaline to lacmoid and decidedly acid to phenolphthalein. 

 If heated at once in a water bath to 98 no coagulation occurs unless 

 a very little acid is previously added. On standing at the room tem- 

 perature for a few hours, protected with thymol, the extract gradually 

 becomes acid, and, if then heated, a large coagulum forms between 50 

 and 55. 



In consequence of this continuous development of acid in the ex- 

 tracts, the conditions which determine the proportion in which bases 

 and acids can combine are constantly changing, and, as the proteins are 

 polyacid bases and nucleic acids are polybasic acids, the salts which are 

 formed under the various existing conditions may be very various. We 

 must therefore expect to find the combinations of protein and nucleic 

 acid which are separated from the extracts of the embryo-meal under 

 different conditions to contain very different proportions of these two 

 substances ; in fact just such products as Osborne and Campbell (336) 

 obtained, for details of the preparation of which the original paper must 

 be consulted. 



The ultimate composition of these products is shown in the four 

 following tables. The first table shows the ultimate composition of differ- 

 ent preparations obtained from the aqueous extract of the wheat embryo, 

 many of which might be called nucleoproteins. The second table shows 

 the composition of the protein part of these preparations after deducting 

 ash and nucleic acid, the amount of the latter being calculated from 

 the phosphorus content of the preparation. It also gives the average 

 composition of the protein part of all the preparations, and, for com- 



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