160 



MORPHOLOGY OF ANGIOSPERMS 



nucleus three spirems are distinguishable, a case observed also 

 in this laboratory by Miss Laetitia Snow in Lilium philadel- 

 phicum. In such cases it is very probable that there is no union 

 of the chromatin (Fig. 73), and it is known that in Pinus there 

 is no fusion of the chromatin of the two sex nuclei before the 



ffigip^ 

 /**&( 



FIG. 73. Paris quadrifolia. A, two polar nuclei in spirem stage ; male .nucleus (ra) 

 shown just above ; B, the two nuclei and male nucleus in spirem stage ; x 1250. 

 After ERNST." 



binucleate stage of the proembryo is reached, and the majority 

 of published figures show this condition. However, Land 3 * 

 describes a complete fusion of the polar nuclei of Silphium 

 before the union with the second male nucleus. 



On the whole, it is to be regretted that the phrase " double 

 fertilization " has been applied to this phenomenon, since it is 

 far from established that it is to be regarded as real fertiliza- 

 tion. During this uncertainty it would seem convenient and 

 sufficient to speak of it as " triple fusion." It is also mislead- 

 ing to speak of the vermiform male nuclei as " antherozoids " 

 or " spermatozoids " in the sense that they are something mor- 

 phologically distinct from the other male nuclei of Angiosperms. 

 Whatever the ordinary male nuclei of Angiosperms may be these 

 vermiform nuclei are. Probably male cells are always organ- 

 ized, and we consider them as morphologically sperm mother- 

 cells; but it is also probable that only the male nuclei become 



