of Pear and 
A. —Photomicrographs of cross-section through Bartlett-pear anther, February 21, 1923, showing 
the pollen mother cells. (X approximately 450) 
B. —Photomicrographs of cross-section through Bartlett-pear anther, March 12,1923, showing mature 
pollen grains. (X approximately 404) 
C—Photomicrographs of longitudinal section through the ovary of the pear, showing developing 
embryo sac. The nucellus is seen as an oval-shaped structure at the center surrounded by the inner 
and outer integuments. The large central cell of the nucellus is the embryo sac. (X approximately 125) 
D.—Same as C, enlarged. This evidently represents an early stage in the development, as only one 
nucleus is found. (X approximately 355) 
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