THE METABOLISM OF PLANTS. 173 



the seedling, and are used by it to form new protoplasm and 

 cell-wall. In considering the changes which they undergo 

 we will begin with the non-nitrogenous reserve-materials. 

 The starch (and cellulose, in the Date) is undoubtedly con- 

 verted into sugar ; this is proved by the detection of sugar 

 as well in the seed as in the seedling, and further by the 

 detection in germinating seeds of an unorganised ferment 

 which possesses the property of converting starch into sugar. 

 The first change which the oils undergo is apparently a de- 

 composition into glycerin and fatty acid, which is probably 

 effected by the action of an unorganised ferment (Schiitzen- 

 berger) ; these substances are then replaced by carbohydrate 

 (Sachs). The glucosides which, as we have seen, are present 

 in some seeds, are decomposed into sugar and other sub- 

 stances also by the action of an unorganised ferment. The 

 absorption of non-nitrogenous reserve-material soon makes 

 itself apparent in the embryo by the formation of a large 

 quantity of temporary starch in its cells, which gradually dis- 

 appears as its growth proceeds. 



With regard to the proteid reserve-materials of the seed, 

 there can be no doubt that they are converted into sub- 

 stances which are diffusible. The visible effect of germina- 

 tion upon the aleurone-grains is, according to Pfeffer, that 

 they swell up and fuse to form a granular viscid mass ; the 

 globoids undergo solution, and so do the crystalloids when 

 they are present. It was thought that the proteids which 

 are insoluble in water (globulins and albuminates) were con- 

 verted into peptone by the action of an unorganised ferment ; 

 von Gorup-Besanez believed that he had extracted a ferment of 

 this kind from the seeds of Vetches, but Krauch has shewn that 

 his results are not trustworthy. In the absence of any evidence 

 to prove the conversion of these proteids into peptone, we 

 must conclude that they are directly split up so as to 

 give rise to amides. The peptone of the aleurone-grains 

 undergoes the same change. It might be thought that the 

 peptone, inasmuch as it is somewhat diffusible, is directly 

 conveyed to the seedling, but this is not the case. In en- 

 deavouring to determine this point I found, in the case of 



