OCTOBEB 2, 1908] 



SCIENCE 



423 



seeds are too gummy to filter and the small 

 amount of the preparations that can be ob- 

 tained is very impure. 



Whether glutelins are constituents of 

 other seeds is a question not yet settled. 

 Most seeds, when exhausted with the 

 several neutral solvents, still contain a 

 small amount of protein which can be ex- 

 tracted with alkaline solutions. It has not 

 yet been definitely determined whether 

 these products are residues of the other 

 proteins extracted by the neutral solvents, 

 or are actually different substances. It is 

 quite conceivable that a part of these other 

 proteins may form combinations with other 

 constituents of the seeds which are not 

 soluble in neutral solvents but are ex- 

 tracted by alkalies, and also that a part of 

 the protein is enclosed in tissues which are 

 dissolved by the alkali and the protein then 

 brought into solution. It is also possible 

 that much or all of this protein is the 

 result of a change, whereby a part of 

 the protein originally soluble in neutral 

 solvents is converted into less soluble 

 products, such as those which have been 

 designated as proteans. The quantity of 

 nitrogen which remains in the thoroughly 

 extracted residues of the seeds is small in 

 the case of most seeds other than the 

 cereals, and it is not probable that many of 

 these contain much, if any, protein belong- 

 ing to the glutelin group. 



4. Albumins are probably present in 

 very small amount in nearly all seeds, and 

 in none of those that I have examined are 

 they present in large amount. The albu- 

 min is probably a part of the physiolog- 

 ically active embryo, and resembles the 

 proteins of animal origin in properties, 

 ultimate composition and proportion of the 

 various products of hydrolysis, more close- 

 ly than do most of the reserve proteins of 

 the endosperm. While the albumins of 

 seeds are like those obtained from animals 

 in the essential properties of solubility in 



water and coagulability by heat, they differ 

 in their precipitation relations towards 

 strong solutions of inorganic salts. 



It is at present almost universally as- 

 sumed that albumins are not precipitated 

 by adding to their solutions an equal 

 volume of a saturated solution of am- 

 monium sulphate, but this is not the case 

 with all of the albumins fi-om seeds. Many 

 of them are also precipitated by saturating 

 their solutions with sodium chloride or with 

 magnesium sulphate, in which respect they 

 differ from animal albumins. 



5. Proteoses similar to those of animal 

 origin have been obtained from all the 

 seeds examined, and from some, proteoses 

 closely resembling hetero-, deutero- and 

 proto-proteose were separated. The 

 amount of such proteose is small in all the 

 seeds which have come under my observa- 

 tion, and it is possible that all of this is 

 formed by enzyme action during isolation 

 of the other proteins of the seeds. 



There are several groups of proteins 

 which occur in animal tissues, which have 

 not yet been proved to exist in plants. 

 The most important of these are those 

 which contain phosphorus. In the yolk of 

 eggs and in the milk of mammals, a large 

 part of the protein which nourishes the 

 developing animal contaias phosphorus 

 which appears to be intimately concerned 

 in the structure of its molecule. No simi- 

 lar phosphorus-containing proteins have 

 been found in seeds, although by analogy 

 such might be expected to occur. It has 

 been asserted that such proteins are found 

 in leguminous seeds, but an examination of 

 the literature will show this assertion to be 

 founded on very little experimental evi- 

 dence. Czapek, in his "Biochemistry of 

 Plants," describes the proteins of seeds as 

 vitellins which doubtless contain phos- 

 phorus. This view, however, has no evi- 

 dence to support it and is quite incorrect. 



The existence of nueleoproteins, that is 



