I 



360 BOTANICAL GAZETTE [November 



One sac indicated the possibility that the synergid may fail to 

 unite in the triple fusion. Fig. 47 is unusually interesting. Some 

 of the nuclei show the tendency to become amoeboid, but the interest 

 is due especially to the condition of the nuclei, all of those that take 

 part in double fertilization having reached the spirem stage not only 

 before fusion, but even before contact. The spirem is well formed 

 in every nucleus, and shortened almost enough to segment into chro- 

 mosomes. It would seem in this case that if fusion does take place, 

 there could be no possibility of a fusion of the chromatin, which would 

 certainly divide into chromosomes from each spirem as it is now 

 formed. Well-formed spirems in different stages of development 

 are common; in fig. 48 the male and female nuclei have formed thick 

 spirems which are evidently clistinct, and while those of the triple 

 nucleus are just as distinct, they are much younger. In the same 

 figure an unusual development of the synergid, or possibly of the tube 

 nucleus, is shown; but as no further indication of division was ever 

 found, there is probably no significance to be attached to it- Fig. 49 

 shows a pollen tube from its entrance into the micropyle to its ending 

 in the sac, the male nuclei being not only elongated but curved. In 

 a few instances there is some distance between the two male nuclei 

 {fi'g^ 50), but this seems to be rather uncommon. The very sharp 

 bend in the tube shown in the last figure suggests some special 

 attraction felt just at this point, directing the tube into the 

 micropyle. 



, ,j 



ENDOSPERM 



The fertihzed egg may divide before the primary endosperm 

 nucleus {figs, ji, 52) and during this di^asion the latter may be in the 

 spirem stage (fig. 51), or resting, or with the spirem just forming; 

 and in one instance the division of the egg was taking place before 

 the second male nucleus had left the pollen tube. The endosperm 

 nucleus, however, may divide first, fig. 53 showing it in late prophase 

 while the egg and male nucleus are barely in contact and the spirem 

 is just beginning to be formed in each. 



With the nuclei of both fusions in the spirem stage the endosperm 

 nucleus may be farther advanced than the egg, one preparation 

 showing its threads very distinct and much thicker than those of the 



