RESEIIVE CELLULOSE. 19 



Instead of being gorged witli reserve both on the walls in the shape of reserve 

 cellulose, and in the cells in the shape of oil and reserve proteids, they are tliin-walled, 

 and contain actively streaming protoplasm, the other matters being in a finely divided 

 state. Compare PI. 1, fig. 2, with PI. 4, fig. 4. Here the cells are active agents of 

 solntion and transfer instead of being passive receptacles. 



In close contact with these vigorons cells are those of the onter layer of the coty- 

 ledon, which contain protein matters in abundance, and oil of a different nature from 

 that found in the endosperm, for with iodine it colors red-brown. The cells deeper in 

 tlie cotyledon contain much starch, as well as those in the neighborhood of the vessels. 



When the section is subjected to the influence of methyl violet and haeniatoxylin, 

 the reserve material takes up the color but little, whereas the cells whose walls are freed 

 from the reserve act as ordinary cellulose. When sections of tlie seed aie placed in 

 congo-red for half an hour, the color is taken up in quantities by those cells with no 

 reserve; and little is taken up by the thick walls, which, as yet, are not affected l)y 

 solution. When, on the contrary, the congo-red is allowed to act for twelve hours, the 

 reserve is more deeply stained than those cells which contain none. Tliis harmonizes 

 with the action observed in the dry seed, when comparison is made with true cellulose. 



With the longer or shorter action of congo-red, the cells of the cotyledon turn 

 slightly bluish, prol)al)ly showing the presence of acid in small quantities, to which 

 congo-red is very sensitive. 



To summarize: nourishment is furnished the young plant by the cotyledon; the 

 source of the nourishment is the material stored in the endosperm, /". e., reserve cellulose 

 from the walls and protein matters from the cells, together with some oil. 



The endosperm first gives up the reserve proteids and oil, next the reserve cellu- 

 lose, which is in part, at least, visible in the cells in the shape of minute oily globules. 



This reappears as oil in the outer layer of cells of the cotyledon, but the end 

 ])roduct is starch, which is found in the cotyledon and in the growing parts of the 

 seedling. The endospei'm cells act with the cotyledon as agents in the chemical and 

 mechanical process of solution and transfer. 



/ri.s' xiJ)!rira presents, during germination, the same phenomena as /r/.s p.se?<r/a- 

 conis. 



Germination of Allium cepa. 



Seeds of 1803 of Al/lnm cepa were sown, April 24, 1894, and on April 28, ger- 

 mination had besrun. 



o 



Sachs^ has shown that the thickening on the walls of the endosperm cells in 

 the seeds of this plant disappears during germination. PI. 4, fig. 5, I, II, and III, 



' S:iclis, Ktumuiigsgescliiclite der AUiiiin ci'iia, etc. Bot. zeit., 1802-0:1. 



