FERTILIZATION AND EMBRYOGENY IN DIOON 
EDULE" 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY I4t 
CHARLES J. CHAMBERLAIN 
_ (WITH PLATES XIV—XvI1) 
Fertilization in Dioon edule occurs from the second week in - 
pril to the second week in May. I have not been able to visit 
Mexico at this season of the year, but through the kindly influence 
of Gov. Teoporo A. Deuesa, who for several years has aided me 
in my investigation of Mexican cycads, and through the constant 
Co-operation of Mr. ALEXANDER M. Gaw, of the State Bureau 
of Information, Xalapa, Mexico, I have been able to secure material 
as regularly as if I had lived at Chavarrillo, where Dioon edule is 
Most abundant. In cones picked at Chavarrillo, April 10, 1905, 
and examined at Chicago, April 21, nearly every nucellus contained 
one or more pollen tubes in which sperms were swimming vigor- 
ously; the next day there were not so many, and three days later 
nearly all pollen tubes had discharged their sperms; but as late as 
May to a few sperms were found. Consequently it would be pos- 
sible for fertilization to occur at this late date, although not very 
probable, for al eggs capable of fertilization would probably have 
been fertili already. A large cone picked at Chavarrillo, April 16, 
T910, and examined at Chicago seven days later, contained embryos 
four times as long as the archegonia; consequently fertilization 
must have occurred as early as April 7. A few embryos in this 
earlier and a week later, but becoming rare beyond these limits. 
While fertilization may be somewhat delayed in cones sent 
such a distance, the processes must be normal, for embryos 
‘Investigation prosecuted with the aid of a grant from the Botanical Society 
[Botanical Gazette, vol. 50 
