RESERVE CEI.IATLOSE. 23 



of the cells begins iniinecliately upon the addition of water and goes on until the 

 structure of the endos2)erni is no longer visible, and a jelly-like niiiss containing 

 distorted and disintegrated bits of cell-contents is all that can be seen. 



When congo-red in water solution is added to fresh cut sections, the process is 

 even clearer, for the forming jelly is colored irregularly through the mass, and, on 

 the edges of the section, the rapid flowing out of the reserve cellulose from the 

 cells in irregular masses can be traced. 



If water with iodine is applied to fresh sections, the mucilaginous mass becomes 

 slowly and evenly colored brown. PI. 5, figs. 6 and 7, show stages in the swelling 

 of the reserve cellulose ; they are from the same section that is represented in fig. 4, 

 Jifter water is ajiplied ; later, oidy a jelly-like mass was to be seen. Chloroiodide of zinc 

 produces a sudden, convulsive swelling of reserve cellulose, the protoplasmic contents 

 of cells is pressed into the center, but connection is still preserved with the primary 

 membranes on the five walls, at the points where least pressure from the 

 swollen corners is felt ; that is, in the middle of each wall. This })roduces a 

 queer star-shaped mass in each cell, the arms of the stars corresponding with 

 each other in the contiguous cells. PL 5, fig. 8, illustrates the curious effect 

 ])roduced upon the cells by this reagent; the swollen masses are not colored. 

 PI. 5, fig. 9, is a sketch of a section, cut in the other direction, also treated 

 with chloroiodide of zinc. 



The greenish oily globules in the cells of the integument have considerably 

 increased in size, since the thickening of the endosperm cells began; they nearly fill the 

 cells. PI. 5, fig. 10, is a sketch of a few of these cells. 



Seeds a few days older than those last described show that the walls, as well as the cor- 

 ners, have been thickened, so that the places, where the canals will appear, are already 

 apparent. The outlines of the walls are smooth, and the thickening is regular. PI. 5, fig. 

 11, shows the condition of the walls at this stage. With water, the peculiarities already 

 noted in the earlier stages appear, the same mucilaginous modification resulting from its 

 application. The contents of the cells are the same, except that the amount of sugar 

 seems to be decreasing. No starch occurs in the seed; the little which in an earlier stage 

 appeared near the chalaza, outside the seed, has disappeaied. 



To summarize: 1. Reserve cellulose appears in the cells of the endosperm soon 

 after the cell-division has ceased. 



2. Its appearance is preceded Ijy a large amount of sugai' in the endos])eriii, wliicli 

 lessens during the process of cell wall thickening. 



3. Much oil appears associated with the sugar in the cells before the walls begin to 

 thicken and is always present in the later stages. 



