THE TIGRIDIA 151 



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

 sure, is a difference that has all-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- 

 combination, thus compelling variations that fur- 

 nish the basis for natural or artificial selection, 

 through which new races are developed. 



All this needs no explanation here, as our 

 earlier studies have made it perfectly familiar. 

 But we may now emphasize the fact that the 

 bulb that produces a new plant carries the 

 hereditary factors of the parent plant substan- 

 tially as they are borne by the ovule or the pollen 

 grain 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 under- 

 ground bud. 



If the ovule could develop without being fer- 

 tilized, 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 

 similar to the parent form, just as the aphids 

 and the bees when parthenogenetically pro- 

 duced, and in a few instances of plants, for 

 example, the violet. Yet there are slight differ- 

 ences even between the different pollen grains 

 and between the different ovules of the same 



