288 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



very granular in the living material, and it could'not be determined 

 whether the granules in question had any specific relation to divi- 

 sion. The failure to find further evidence of these granules after 

 stud^ang a great number of living cells, makes one doubt their 

 relation to cell-division. That such rows of granules might appear 

 in any part of the cell is indicated by the evidence from fixed 

 material presented below. 



After the homoeotypic mitosis the protoplast assumes a spheri- 

 cal form within the cell-wall, which conforms to the protoplast on 

 its inner surface, but which may have an outer surface of various 

 forms. It would appear that the mother-cell-wall is of such 

 viscosity as to yield to the pressure due to the cell-turgor, but 

 that is has too high a coefficient of viscosity readily to assume a 

 spherical form itself when freely suspended in water. As Hof- 

 meister suggests, there may be a difference in the viscosity of the 

 inner and outer layers of the wall, so that the one takes the form 

 of the enclosed protoplast, while the other retains some of the 

 effects of the external pressure under which it existed within the 

 pollen-chamber. In other words, the outer portion of the cell- 

 wall has an elasticity which operates against its external form 

 being permanently changed by the application of transitory 

 pressure. 



When the daughter nuclei become completely re-organized they 

 withdraw as far as possible from each other in the cell, usually as- 

 suming a tetrahedral arrangement. Soon the cell-cavity becomes 

 lobed (fig. 5). It seems that this is not the consequence of the 

 protrusion of the plasma membrane in the region of each nucleus, 

 as Farmer and Moore (17) described for similar cells of Aneiira; 

 but it appears rather that it is due to furrowing of the plasma 

 membrane along the plane midway between each pair of nuclei. 

 The first indication of the furrowing is to be found in the flatten- 

 ing of the protoplast on four sides, each of which is parallel to the 

 plane of three nuclei, so that the entire protoplast assumes the form 

 of a tetrahedron, the nuclei lying near the corners. A depression 

 appears in the center of each flattened surface, and the depression 

 of each face is connected with that of each of the others by a 

 furrow which bisects the edge of the tetrahedron across which it 

 passes. These furrows may either take the form of a broad con- 

 cavity with smooth curves, equaling in width about one half of 



