258 PHYSIOLOGY OF NUTRITION. 



2-4 mm., there is present in these organs, and in the lower 

 plants of the stalks of the cotyledons, but little asparagin. Seed- 

 lings with roots 30 or 40 mm. in length, and whose cotyledons 

 have not yet been thrust far above ground, contain asparagin in 

 the root; it is, however, absent at the tip of the root. In the 

 cortical cells of the hypocotyl, and in the lower parts of the stalks 

 of the cotyledons, asparagin is present. It is, however, still 

 absent in the blades of the cotyledons. When germination has 

 advanced so far that the cotyledons are expanded, asparagin is 

 present in them. In their stalks, and especially in the hypocotyl, 

 very large quantities of asparagin are now present. It occurs, 

 however, only in the cortical cells ; in the elements of the vascular 

 bundles it is, as is always the case, entirely wanting. When the 

 epicotyl lengthens, asparagin is to be detected here also, while 

 the other organs of the seedlings, especially the hypocotyl, 

 gradually become poorer in asparagin. As the development of 

 the plant proceeds, under normal conditions of vegetation, the 

 asparagin entirely disappears from all the organs, since now, in 

 consequence of the activity of assimilation, such large quantities 

 of non-nitrogenous organic substances are produced, that the 

 nitrogenous bodies formed by the dissociation of the physiological 

 elements can at once be reworked up entirely into proteids. The 

 fact should also be noted that, in proportion as the formation of 

 asparagin advances during germination, the quantity of proteid 

 reserve in the receptacles of reserve material diminishes. If, for 

 example, we examine cotyledons of Lupinus when the elongation 

 of the epicotyl is beginning, we find that the cell contents are 

 already much cleared, and treatment of the sections with Iodine 

 shows that the quantity of proteid in the cells is no longer ex- 

 cessive. 1 



To prove positively that the reformation of proteid from 

 asparagin can only be effected with the help of non-nitrogenous 

 bodies, we fill two flower-pots with garden soil or with sand, water 

 well Avith food solution, and lay in them a few seeds of Lupinus 

 luteus. The plants in one pot are grown under quite normal 

 conditions in front of a window. The other pot is also exposed 

 to light, but it is placed in the apparatus described in 16, and the 

 plants grow in air deprived of Carbon dioxide. They are con- 

 sequently unable to assimilate, and hence their growth is arrested 

 when the second leaflet has unfolded. Now, and even until they 

 die, large quantities of asparagin are to be detected in the organs 



