ON THE TIGRIDIA 



union of two different racial strains, one borne by 

 the pollen and the other by the ovule. This, to be 

 sure, is a difference that has very important prac- 

 tical bearings, inasmuch as the union of two dif- 

 ferent hereditary strains gives opportunity for the 

 blending of hereditary factors and their re-com- 

 bination, thus compelling variations that furnish 

 the basis for natural or artificial selection, through 

 which new races are developed. 



All this needs no explication here, as our 

 earlier studies have made it perfectly familiar. 

 But what I wish now to emphasize is the fact that 

 the bulb that produces a new plant carries the 

 hereditary factors of the parent plant substantially 

 as they are borne by the ovule or the pollen gram 

 that the same plant puts forth on its aerial stalks, 

 and exactly as the bulb of any plant in fact, the 

 bulb of any plant is only a fat, immature, under- 

 ground bud. 



If the ovule could develop without being 

 fertilized, or if the pollen could grow into a plant, 

 the result in either case, we may reasonably 

 assume, would be a reproduction of the plant 

 closely similar to the parent form, just as the 

 aphids and the bees when parthonogenetically 

 produced, and in a few instances of plants, for 

 example, the violet. Yet there are differences 

 between the different pollen grains and between 



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