Dorsey: Pollen Sterility in Grapes 



249 



DEGENERATION OF BOTH NUCLEI 



In some cases both nuclei of the pollen grain degen- 

 erate. At the left is a photomicrograph of a 

 pollen grain from Brighton, in which this has 

 taken place; at the right is a camera lucida draw- 

 ing much more enlarged of the same process, in 

 another grain of the same variety. Note irreg- 

 ular shape of both nuclei. (Fig. 6.) 



Finally, then, in the case of the grape, 

 if sterility results from degeneration in 

 the generative nucleus which prohibits 

 normal functioning of the pollen, it is 

 clear, that to overcome the defects of 



self sterility in any variety, it will be 

 necessary to continue the practice 

 firmly established by some of the earlier 

 workers of mixing varieties in the 

 vineyard. 



REFERENCES 



Beach, S. A. Self-Fertihty of the Grape. N. Y. State Exp. Sta. Bull. 157:397-441. 1898. 



Beach, S. A. Fertilizing Self-Sterile Grapes. N. Y. State Exp. Sta. Bull. 169:331-371. 1899. 



Booth, N. O. (a) A Study of Grape Pollen. N. Y. State Exp. vSta. Bull. 224:291-302. pis. 

 1-6. fig. 1. 1902. 



Dorsey, M. J. Variation in the Floral Structures of Vitis. Bull. Torr. Bot. Club 39:37-52. 

 figs. 1-24. 1912. 



Dorsey, M.J. Pollen Development in the Grape with Special Reference to Sterility. Minn. 

 Agr. Exp. Sta. Bull. 144:1-60. pis. 1-4. 1914. 



Munson, T. V. Foundations of American Grape Culture. 252 pp. pis. 1-89. figs. 13. 

 Denison, Texas. 1909. 



Reimer, F. C. and Detien, L. R. Self-Sterility of the Scuppernong and Other Muscadine Grapes 

 N. C. Exp. Sta. Bull. 209:5-23. figs. 1-13. 1910. 



Whitten, J. C. The Grape. Mo. Exp. vSta. Bull. 46:33-76. pis. 1-7. 1899. 



Great Men and How They Are Produced 



In order to call attention to his offer which is now in the hands of the American 

 Genetic Association, Casper L. Redfield (Monadnock Block, Chicago, 111.) has 

 issued a pamphlet with the title "Great Men and How They Are Produced." 

 It gives partial genealogies for 571 eminent men, showing that in most cases such 

 men are the product of slow breeding — that is, with an unusual amount of time 

 between generations. Mr. Redfield has offered two prizes of $100 each to the 

 American Genetic Association, if any one can bring forward instances of really 

 great men produced by rapid breeding. The offer remains open until December 

 31, 1915, and its details can be learned from the Journal of Heredity, July, 1914, 

 or from Mr. Redfield or this Association. 



