88 The Botanical Gazette. [March, 
the colorable nuclear elements. While the division is im 
what is commonly called the ‘‘spindle” stage the astrocenters 
each divide and thus form at each end of the old nucleusa 
pair of directive spheres. With the development of the 
nuclear membranes in the two daughter-nuclei the spheres 
take up their normal positions and the process may be re 
peated as the divisions continue. It is this contribution to 
our knowledge of the morphology of the astrocenter that 
counted so much for Guignard in the assignment of the Prix 
Bordin, just awarded him by the French Academy. 
chromosomes themselves. This is brought about as follows 
in L. martagon—the plant of particular study: 
4. After the pollen tube has reached the egg-cell, which 
lies in the embryo-sac immediately behind the two syne 
gidae, the male nucleus is seen to pass over to the egg-cell and 
take up a position beside it in such a way that the two direc: 
tive spheres are in contact with each other. The two nuclel 
: Sle directive sphere lies at each pole of the segmn 
tation nucleus. These become the astrocenters for the segme® 
tation nucleus. i : ly 
- 
membranes lying b 
i etween the two copulating nuclei an 
formation of the pla pasos 
: en: 
te in the segmentation nucleus the mal a 
