538 Jeffrey. — On Polyembryony in 
of Strasburger on polyembryony in Funkia , N othoscordon , 
Euonymus , Citrus , &C . 1 
In these forms the multiplicity of embryos was shown to be 
due to the adventitious buds derived from the nucellus growing 
into the cavity of the embryo-sac after fertilization. Later 
Guignard has described in Mimosa Denhartii a polyembryony 
arising from the fertilization of one or both of the synergids in 
addition to that of the normal egg-cell 2 . 
He has not explained however how the two generative 
nuclei of the pollen-tube are able to fertilize the nuclei of the 
three cells which give rise to the embryos. He also observed 
polyembryony in Schrankia uncinata , but from lack of 
material was unable to discover its mode of origin. 
More recently Dodel and Overton have described polyem- 
bryony in Iris sibirica , which they refer to synergidal 
fertilization 3 . 
In February of this year (1895) Tretjakow published an 
account of polyembryony in Allium odorum , originating from 
the formation of embryos from the antipodals 4 . 
It will be seen from the above that the place of origin 
of the supernumerary embryos being considered, there are 
two kinds of polyembryony which may be conveniently 
termed extrasaccal (Funkia, N othoscordon , Sic.), and intra - 
saccal (Mimosa, Iris, and Allium odorum). The embryos 
of Erythronium are intrasaccal, but differ from the others 
described in all taking their origin from the fertilized egg-cell. 
The youngest ovules of Erythronium americanum pro- 
curable in the early spring show the embryo-sac in the binu- 
cleate state. The two nuclei divide in the usual way, giving 
rise to four and then to eight nuclei. The nuclei of the 
micropylar and antipodal ends of the embryo-sac are generally 
markedly different in size, but sometimes the micropylar and 
1 Ueber Befruchtung und Zelltheilung, Jen. Ztsch. Bd. XI. Ueber Polyembryony, 
Jen. Ztsch. Bd. XII. 
2 Annales des Sci. Nat., Ser. 6, tome XII. 
3 Dodel, Beitr. z. Erkenntn. der Befruchtungsersch. bei Iris sibirica. Zurich, 1891. 
4 Ber. d. Deutsch. Bot. Gesells., Feb. 1895. 
