HISTORICAL SKETCH 



15 



orange seeds, and other instances of a similar nature were listed by- 

 Alexander Braun (1859). In no case, however, had the origin of 

 the abnormality been satisfactorily studied from the developmental 

 point of view. Strasburger, in 1878, demonstrated for the first time 

 that in Funkia (=Hosta) ovata, Coelebogyne ( = Alchornea) ilicifolia, 

 Nothoscordum fragrans, and Citrus aurantium, the nucellar cells lying 

 close to the apex of the embryo sac become richly protoplasmic and 

 divide to form small groups of cells which project into the cavity of 

 the embryo sac and grow into embryos (Fig. 13). Subsequent work 



B D 



Fig. 13. Development of ad ventive embryos in Funkia (= Hosta)ovata. A, upper 

 part of nucellus and embryo sac. B,C, enlargement and division of some of the 

 nucellar cells. D, more advanced stage, showing young zygotic embryo and several 

 nucellar embryos. (After Strasburger, 1878.) 



by others revealed further possibilities, such as an origin of embryos 

 from the cells of the integument, or from those of the suspensor, or 

 from components of the embryo sac other than the egg. In Allium 

 odorum, Tretjakow (1895) and Hegelmaier (1897) showed that even 

 antipodal cells could give rise to embryos. 



Discovery of Syngamy. These were all notable advances, but 

 the most important of all was Strasburger 's (1884) discovery of the 

 actual process of syngamy, or the fusion of the male and female 

 gametes. In a memorable paper, entitled "Neue Untersuchungen 

 uber den Befruchtungsvorgang bei den Phanerogamen," he cor- 

 rected some of the mistakes he had made in 1877 on the organization 



