296 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



At the middle of some of the spindle fibers at this stage there 

 appear to be thickenings, but these little masses may also be found 

 apparently unassociated with fibers. Occasionally one or two 

 fibers nearer the center of the mother-cell may be found with a 

 dense granular mass near its middle point. Such sporadic appear- 

 ances are doubtless responsible for the statements by many 

 authors that the division is of the ordinary cell-plate type; but 

 there is no evidence that the fibers shorten at this time or at 

 any time in the process of division. They are never seen to pull 

 away from the nuclei and no plate or similar structure across the 

 equator of the spindle is formed. The fixed material shows no 

 plasmolysis in these stages, and the red, blue, and orange stains 

 were well balanced. No difficulties in technique, such as Stras- 

 burger reports having encountered in the dicotyledons he studied, 

 were here experienced. In a number of instances rows of granules 

 were found; but these are as frequently, if not more often, located 

 in other parts of the cell than the equatorial planes. Such a one 

 may be seen in the upper left-hand corner of figure 27, in the 

 lower right-hand corner of figure 28, in figure 30, and in the 

 lower left-hand corner of figure 32. They are probably in most 

 cases the result of chance distribution of granules, and only in 

 three instances, figures 27, 39, and 31, can they be considered 

 as having any relation to cell-division. The last-named figure 

 presents the nearest approach to a cell-plate which could be found. 

 It might be argued that these rows of granules in various positions 

 between the nuclei are composed of material which is diffusing 

 from the nuclei to the plane of division, but no accumulation of 

 such material in that plane in the form of a plate could be found. 

 A slight depression or concavity appears almost immediately 

 (fig. 27) in the plasma membrane at the equatorial plane of the 

 spindle. At first it is rather abrupt, though the exact center of 

 the concavity is always a smooth curve and never a sharp edge. 

 Soon, however, this broadens into a wide smooth curve (fig. 28), 

 giving the mother-cell a loljcd appearance. Spindle fibers may 

 run to the plasma membrane in the region of the furrow, but 

 there seems to be no tendency for them to be oriented thereupon 

 any more than upon other points along the membrane. The 

 spindles seem at this time to take on a little more definite organiza- 

 tion. Not so many fibers are found crossing each other, and the 



