No. 526] SEXUAL REPRODUCTION IN AN GIO SPERMS 611 



the polar nuclei in a number of plants lias been asso- 

 ciated with, if not actually regarded as, a sexual act, the 

 phenomenon will receive a brief mention. In 1897, the 

 writer (Mottier, '97) called attention for the first time 

 to the fact that the second male nucleus applied itself 

 to one of the polar nuclei in Lilium Ma rf<if/m/ , and 

 shortly after that date the actual union of tliis male 

 nucleus with the endosperm nucleus of the emhryosac 

 was reported for various plants by different observers. 

 Guignard spoke of this nuclear union as a second fe- 

 cundation, hence arose the idea of "double fecundation" 

 in phanerogams. The fusion of the two polar nuclei and 

 the second male nucleus resembles physically the real 

 sexual union, as do also nuclear fusions in ordinary 

 vegetative cells wherever such may occur. It recalls 

 a sexual act in subsequent behavior, for it is maintained 

 that endosperm thus arising is of a hybrid character, 

 and that this hybrid character is due to the hereditary 

 influence of the male nucleus. The hereditary influence 

 of the second male nucleus upon the endosperm we may 

 admit for the sake of argument, for whatever else this 

 phenomenon may signify, it certainly shows the greater 

 importance of the nucleus in the transmission of char- 

 acters. But, that this union of nuclei in the endosperm 

 cell is not a sexual process, as defined in a foregoing 

 paragraph, is seen in the fact that the endosperm is 

 merely a continuation of the female gametophyte, de- 

 veloped subsequent to fertilization of the egg, and for 

 the nourishment of the sporophyte, just as a fern pro- 

 thallium may continue its development, following the 

 fecundation of an egg and its subsequent development 

 into the embryo fern. 



Tn a group of organisms in which a structure or func- 

 tion is so universally present, the absence of the same 

 in any one or several of such organisms elicits at once 

 our attention, and, in this respect, apogamy and par- 

 thenogenesis become of special interest. Although 

 apogamy and parthenogenesis do not involve the sexual 



