CHAPTER XII 

 POLLINATION AND THE STERILITY PROBLEM 



The sexual relation of plants and the union of male and 

 female elements to the proper development of fruits have 

 been known since ancient times, but it is only within the 

 past quarter of a century that marked progress has been 

 made in understanding the causes of these phenomena and 

 many of them are not yet fully apprehended. In studying the 

 effect of pollination on the setting of orchard fruits, one 

 should keep in mind that two points are involved: first, the 

 importance of pollinization in effecting the development of 

 fruits even though no actual fertilization takes place; and 

 second, that as a result of such pollination there may be 

 fertilization and development of the embryo, resulting in 

 viable seed capable of producing new progeny. From the 

 standpoint of the breeder, the latter is paramount (i. e., the 

 production of fertile seeds), but the orchardist is concerned 

 primarily with the former of the two results. The vegetable- 

 grower, on the other hand, may be interested in the pro- 

 duction of viable seed, depending on the crop involved, 

 and with the nut-grower, it likewise becomes a matter of 

 practical importance. 



252. Investigations in pollination. — Centuries prior to 

 the Christian era, the peoples of Egypt and Mesopotamia 

 were cultivating dioecious plants for food and practicing 

 artificial pollination of the fig and date palm.^ However, the 

 first scientific investigation of this problem was not forth- 

 coming until A. D. 1694 when Camerarius proved that fer- 



1 Johnson, D. S. Sexuality in plants. Jour. Heredity, 6: 3-16. 1915. 



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