Chap, in The Morphology of the Flower 101 



constitute the primary endosperm and to be partly sexual, 

 and partly vegetative. The sexuality of the oosphere 

 is certain; the synergidae have, in his opinion, been 

 modified to perform a secondary office in the process of 

 fertilization. He taught further that the archegonia of the 

 Pteridophyta and of the Gymnosperms are reduced in the 

 Angiosperms to a single one, which is represented only by 

 its oosphere. 



His anatomical researches explained the nature of the 

 filiform apparatus of Schacht, which was seen to be the 

 elongated ends of the synergidae. 



Strasburger's hypothesis of the nature of the prothallium 

 in the Angiosperms was completed by the suggestion that 

 its development is arrested at the stage described, and 

 resumed after fertilization of the oosphere, by the develop- 

 ment of a secondary portion, the so-called endosperm, 

 from the definitive nucleus, itself the result of the fusion 

 of the polar nuclei. 



Goebel held the opinion in 1880 that the antipodal cells 

 correspond to the large-celled endosperm of Selaginella. 



The synergidae were recognized to be potential sexual 

 cells by Dodel in 1891. He described their fertilization 

 in Iris sibirica. Similar observations were made by 

 Chauveaud in 1892, when investigating some cases of 

 polyembryony in Vincetoxicum. The fertilization of one 

 of them was observed by Schwere in Taraxacum four years 

 later. Guignard, as long ago as 1881, found in a species 

 of Mimosa three embryos side by side, suggesting a develop- 

 ment of one from each of the synergidae as well as from 

 the oosphere. At the time he did not suggest this order of 

 development as certain, holding it to be possible that they 

 might be due to budding from the early segments of the 

 zygote. He observed a similar occurrence of two embryos 

 in Naias in 1901, but again he admitted the possibility 

 of a similar explanation. 



