THE SEED PRODUCTION OE PINUS SYLVESTRIS. 5£'| 



similar to that figured by Chamberlain I have occasionally 

 found, but nothing exactly like it. 



That a fusion nucleus is not formed, I do not consider 

 proved. In more than one instance I have found the 

 nucleus of a fertilised egg having all the appearance of 

 complete fusion, and one case at least, of which there can 

 be no reasonable doubt (fig 14). I hope later to decide 

 this point. For the present I leave it here. 



Whatever may be the course of procedure, the time 

 taken is very short, for in two days the first division is 

 complete, and about 24 hours later the resulting nuclei 

 have again divided. These four nuclei are usually 

 produced in the upper half of the egg, occasionally it may 

 be about the centre ; when first clear of the spindle they 

 are about 40 microns in diameter ; they at once pass to the 

 base of the egg, impelled probably in some way by the 

 fibres that soon invest them. 



By the time the base is reached they appear to have 

 increased somewhat in size ; this, however, is difficult to 

 determine owing to their very variable dimensions ; 

 although the average size of these when ready for division 

 is about 55 microns, many are found much smaller, others 

 much larger ; they vary in fact between 40 and 70 microns. 



The fibres investing the nuclei are exceedingly fine, 

 but densely packed. They are now arranged in such a 

 way that they appear to be vertical walls forming four 

 open pockets, in each of which there is a nucleus, and as 

 walls they have generally been regarded. That they are 

 not walls is at once evident when the nuclei pass into the 

 spindle stage of division, for at this time the fibres have 

 disappeared, and no trace of walls can be detected. 

 During this division transverse walls make their appear- 

 ance upon the spindle in the usual way. While this 

 division is in progress there has been a re-aggregation of 



