612 THE AMERICAN NATURALIST [Vol. XLIV 



phenomena is likely to modify profoundly our views of 

 sexual reproduction, especially if a series of generations 

 of apogamously produced plants be compared with a 

 series of sexually produced individuals, of the same or 

 related species, in regard to the subject of variation, 

 individual vigor, manner of propagation, transmission 

 of certain characters, etc. The term apogamy is here 

 used to signify the development into an embryo of the 

 egg-cell possessing the double or 2x number of chromo- 

 somes without the union with a sperm nucleus from the 

 pollen-tube (somatic parthenogenesis of Winkler, par- 

 thenopogamy of Farmer and Digby). It is not deemed 

 desirable to connect the word parthenogenesis with such 

 a process, for a reproductive cell, although developed 

 morphologically as a gamete, is not so considered unless 

 it contain the reduced number of chromosomes. Accord- 

 ingly, the term parthenogenesis will be applied only to 

 the development into an embryo sporophyte of an egg 

 containing the x number of chromosomes. 



In recent years several notable cases of apogamy 

 among phanerogams have been described, among which 

 may be mentioned Antennaria alpina by Juel (1900), 

 species of Alchimilla, especially of the group Eual- 

 chimilla by Murbeck and Strasburger ('04), Taraxacum 

 officinale by Juel, Wikstroemia, by Winkler, together 

 with several others from different families of plants. 

 In Antennaria alpina, for example, the tetrad divisions 

 do not take place in the megaspore mother-cell which 

 functions at once as the megaspore. Naturally this cell 

 contains the diploid number of chromosomes. From 

 this cell there develops an apparently normal embryo 

 sac, with the exception that the polar nuclei do not unite. 

 The cell which represents the egg develops without 

 fecundation into an embryo sporophyte. The process 

 in the other species mentioned is in the main similar to 

 that of Antennaria alpina, differing only in certain de- 

 tails, which may not be enumerated here. While, in 

 these apogomous species, an apparently normal gameto- 

 phyte develops, it may be very seriously questioned 



