
Fic. 463. Megaspore mother cell and megaspores of Zamia Jloridana 
Center, megaspore mother cell within the nucellus, the curved lines outside the 
nucellus showing location of the integument; left, four megaspores formed 
by the division of megaspore mother cell ; right, the three apical megaspores 
have begun to disorganize, while the lowest, which will give rise to the female 
prothallus, is enlarging. (Redrawn after F. Grace Smith) 

Fre. 464. Longitudinal section through megasporangia of C 
‘yeas rumphit 
Left, megasporangium some months before fertilization ; 0, outer layer of the 
integument; s, stony layer of the integument; i, inner fleshy layer of the in- 
tegument; n, nucellus; p, female prothallus; a, archegonium. Center, an older 
megasporangium ; the prothallus has enlarged while the nu 
disappeared. Right, an embryo has grown from one of the archegonia and 
penetrated into the prothallus. (x 19 
cellus has largely 
Ps 
a 
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ae, ee ee eee 
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