152 



ARCHEGONIATES. 



the nucleus, but, in a number of cases in this stage and in a still later 

 stage, they have been found nearer together, frequently less than 45 

 apart." 



The first indication of a differentiation in the blepharoplast as it 

 increases in size is seen in the formation of an outer wall or membrane. 

 The generative cell, which has remained nearly spherical, increases in 



FIG. 61. Prothallium and a dividing generative cell of Zamia. (After Webber.) 



A, prothalliuiu in which generalive Cell has become large and elongated ; the blepharoplasts have taken 



positions on opposite sides of nucleus, corresponding to longitudinal axis of pollen tube; starch 

 grains have begun to appear in stalk cell. 



B, division of generative cell, nucleus in anaphase, showing hyaline cytoplasmic areas around poles ; 



the blepharoplasts, whose outer membranes have separated into pieces or segments, are not con- 

 nected with spindle. 



size and becomes elliptical or oblong, its major axis nearly coinciding 

 with the longitudinal axis of the pollen tube (Fig. 61, A). The 

 blepharoplasts by this time have taken a position on opposite sides of 

 the nucleus on the line of the major axis of the cell. The kinoplasmic 

 radiations are slightly more prominent than the lamellae or fibrillae of 

 the cytoplasmic reticulum into which they run and disappear (Fig. 61 , A) . 



