GNETALES— EPHEDRA 



381 



not rare; but Land^^' found many binucleate cells in the normal 

 jacket. 



Dr. Stephanie HERZEELD^^a figured and described a fusion of the 

 second sperm nucleus with the ventral canal nucleus, and did not 

 hesitate to call it double fertilization in the angiosperm sense (fig. 



363)- 



In conifers there have been reports of divisions in the top of the 

 egg, variously attributed to divisions of the 

 second sperm, or the ventral canal nucleus; 

 and HuTCHiNSON^'^s described and figured the 

 fusion of the second sperm with the ventral 

 nucleus in Abies halsamea. 



That nuclei in the rich protoplasm at the 

 top of the egg should divide, seems very nat- 

 ural, whether the division might be pre- 

 ceded by any fusions or not; and it also seems 

 probable that any such product would serve 

 to nourish the growing embryo; but that 

 there is any genetic continuity between this 

 phenomenon and the double fertilization in 

 angiosperms — in other words, that the angio- 

 sperms inherited double fertilization from 

 the gymnosperms — ^seems more than doubtful. 



Fig. 363. — Ephedra 

 campylopoda: "double 

 fertilization": e, egg 

 nucleus; Si, first 

 sperm; v, ventral nu- 

 cleus; S2, second 

 sperm. — After Herz- 



FELD.2« 



EMBRYOGENY 



Strasburger,^^'^ in 1876, outhned the embry- 

 ogeny of Ephedra altissima, and Land, in 1907,^^' 

 made a thorough investigation of E. trifurca. 



There is a free nuclear period with, usually, 8 free nuclei, which 

 do not sink to the bottom of the egg, but are somewhat evenly dis- 

 tributed throughout the protoplasm (fig. 362). Around each of these 

 nuclei there is organized a cell, which is a young embryo. So there is 

 polyembryony without any cleavage. Usually from three to five 

 of the young embryos begin to develop (fig. 362). The nucleus of the 

 embryo cell divides, but the formation of a wall between the two 

 nuclei is delayed until a suspensor tube has been formed. The em- 



