424 



SCIENCE 



[N. S. Vol. XXVIII. No. 718 



of compounds of nucleic acid with protein, 

 is a different question and involves con- 

 sideration of the chemical nature of these 

 substances as now described. The nucleo- 

 proteins are, so fax as I know, always de- 

 scribed as phosphorus-containing proteins, 

 and the phosphorus seems to be generally 

 considered as a constituent of their mole- 

 cules. This, of course, is strictly true even 

 if the combination be only that of a base 

 and an acid, but from the standpoint of 

 protein chemistry it makes a great deal of 

 difference whether this union is that of a 

 salt, or one in which the phosphorus-con- 

 taining groups are in intimate organic com- 

 bination within the protein molecule. 

 That true nucleic acids exist abundantly in 

 seeds has been demonstrated by investiga- 

 tions made in my laboratoiy on the wheat 

 embryo. In these investigations a great 

 deal of attention was devoted to the pro- 

 tein compounds of the nucleic acid, but 

 all the evidence obtained indicated very 

 plainly that these were simply protein 

 nucleates, the composition of which de- 

 pended solely on the conditions prevailing 

 at the time of precipitation. That similar 

 combinations exist within the embryo is 

 practically certain, but that any of the 

 combinations actually isolated were iden- 

 tical with the combinations that exist in 

 the seed, I consider highly improbable. 

 "Whether the nueleoproteins that have been 

 described from animal tissues are more 

 definite and intimate combinations between 

 the nucleic acid and the protein than are 

 the protein nucleates just mentioned, I am 

 not prepared to say, biat I think that 

 nueleoproteins deserve more consideration 

 from this point of view than they have 

 received. 



"Whether, or not, true glycoproteins are 

 contained in seeds, remains to be demon- 

 strated. That a large part of the seed pro- 

 teins are entirely free from any carbo- 

 hj^drate yielding group, is proved con- 



clusively by the fact that these yield no 

 trace of the Molisch reaction. That those 

 that give the Molisch reaction contain a 

 carbohydrate group as a constituent of 

 their molecule is seriously to be questioned, 

 for it is not possible to obtain even traces 

 of furfurol from them. 



If one considers how small an admixture 

 of carbohydrate gives a very strong reac- 

 tion with the Molisch test, it may well 

 be asked whether this reaction is not some- 

 times caused by a slight contamination. 

 The possibility of this is so great in the 

 preparations of proteins extracted from 

 seeds containing a great variety of carbo- 

 hydrates, glueosides and nucleic acids, that 

 conclusions drawn from the results of the 

 Molisch reaction have value only when this 

 turns out negatively. 



In plants no representative has yet been 

 found of the group of albuminoids which 

 form in animals so large a part of the 

 skeleton, connective tissues, the skin and 

 its appendages. 



Although the nucleated cells of the 

 wheat embryo are rich in nucleic acid 

 which closely resembles in its properties 

 and striieture the nucleic acids obtained 

 from the nucleated cells of animals, no 

 substances have yet been found in plants 

 which resemble the protamines which in 

 combination with nucleic acid occur so 

 abundantly in the spermatozoa cells of 

 animals. Such substances are to be sought 

 in the pollen cells of plants, but as yet no 

 attempt has been made to isolate them, 

 owing to the difficulty of obtaining a suffi- 

 cient supply of material, and the fact that 

 the nucleus of the cell forms so small a 

 part of the whole structure. 



PRODUCTS OF HTDROLTSIS OF SEED PROTEINS 



Of the known primary products of pro- 

 tein hydrolysis all but one (diamino-tri- 

 oxydodecanie acid, as yet obtained only 

 from casein) have been isolated from seed 



