134 Taylor — A Morphological and Cytological 



that of the ovular cavity, but is at first delayed, later progress- 

 ing more rapidly so as to fill the cavity often with accompany- 

 ing crumpling of the cotyledons. 



Abnormalities of pollen formation, such as giant grains and 

 unseparated tetrads, were seen, and also abnormalities in the 

 formation of the embryosac. Tricarpellary ovaries appeared 

 in several forms, and a twin embryo was observed, with one 

 individual much larger than the other. 



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Explanation of Plates 



Plate VI — Stages in Reduction Divisions, Pollen Formation in Acer negundo. 

 All Figures Reproduced X2250. 

 Fig. I. Resting nucleus after last archesporial division. 

 Fig. 2. Nucleus showing approaching leptonema. 



