202 LECTURE X. 



as sources for the production of plant proteins. We note great changes 

 as soon as germination begins; in fact, the entire cell contents are drawn 

 upon. We have already considered the conversion of the carbohydrates 

 into fats, and vice versa. Besides such processes hydrolysis undoubtedly 

 causes other metabolic changes to take place. The proteins are disin- 

 tegrated into their components by the activity of proteolytic ferments. 

 Complicated products. " peptones/' * are first formed, and finally amino 

 acids, which, at least in part, are then decomposed further. We may 

 compare the beginning of germination with the intestinal processes. The 

 purpose is in many respects the same. The germinating cell disintegrates, 

 in order to utilize the various elementary components for the construction 

 of a new cell body. We are still undecided whether the protein molecule is 

 completely, or only partially, disintegrated by hydrolysis. Asparagine 

 has been detected in germinating legumes, while glutamine has been 

 observed in other cases. The amount of asparagine may be increased by 

 germinating in the dark. We are still unaware of the significance of the 

 formation of asparagine. It is possible that it does not participate further 

 in the construction of albumin, but that it acts as an intermediate step 

 to other- nitrogenous substances; or, even, that it has nothing further to do 

 with such substances, but now enters into relations with the carbohydrates 

 and fats. 



That asparagine does not directly participate in the synthesis of albumin, 

 which immediately follows its breaking down, is evident from the fact 

 that it does not dimmish to the same extent that the albumin formation 

 progresses. 



We will add here that the seedlings at the beginning of their existence 

 also disintegrate their other constituents, the nucleins, fats, etc., into the 

 components. It reconstructs everything anew. 2 We may compare the 

 metabolism of this germinating seedling with that of the animal. 



When we take everything that we know about the formation of the 

 proteins in the vegetable kingdom and their albumin metabolism into 

 consideration, we find it very difficult to formulate any distinct conception 

 of what actually occurs, based on experimental results. We have felt 

 that we ought to consider briefly this subject here, because, as we have re- 

 peatedly said, we can expect to have a complete understanding of biological 

 processes only when we have as broad a foundation as possible. There is 

 no sharp dividing line between the plant and animal kingdoms. It would 

 be a gross error to try to separate the biological investigations in these two 

 fields. The absolute dependence of the animal organism on the products 

 of the vegetable kingdom forces us to consider in detail the biological 

 chemistry of plants. 



1 W. R. Mark: Z. physiol. Chem. 42, 259 (1904). 



2 Cf. among others, J. R. Green and H. Jackson: Pr. Roy. Soc. 77 (B), 69 (1905). 



