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FUNDAMENTALS OF FRUIT PRODUCTION 



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Plate II. — Successive stages in the development of tlie pollen grain of the grape. 

 Fig. 1, section of anther showing epidermal, middle, tapetal and mother-cell layers. Figs. 

 2 and 3, later stages in these same layers. Fig. 4, a pollen-mother-cell. Fig. 5, the tetrad 

 stage in the pollen-mother-cell. Fig. 6, a microspore or pollen grain, before its liberation 

 from the pollen-mother-cell. Fig. 7, a pollen grain of the Concord grape. Fig. 8, the genera- 

 tive cell in a mature pollen grain. Figs. 9-12, various stages in the development of the 

 generative and vegetative nuclei, but in each instance one or both nuclei are undergoing 

 degeneration. Fig. 13, the normal generative cell and vegetative nucleus of a pollen grain. 

 (After Dorsey.^^) 



