304 GENETICS 



tained a combination AABBCCDD, etc. This contains 

 more of the genes that tend to give increased number of 

 leaves than either of the parent stocks; therefore it carries 

 more leaves than either of the parent stocks. 



In analogous ways, by crossing diverse races and selecting 

 among their descendants, it is possible to obtain stocks that 

 exceed the originals in dimensions, numbers of parts, depth 

 of color, vigor, power of resistance, and the like. There 

 is little doubt that the same method of procedure gives 

 similar results with relation to capabilities, temperament, 

 mental characteristics of various kinds, in man. Thus by 

 selective mating it is entirely possible that human stocks 

 could be produced that would be superior in respect to such 

 characteristics to any now existing. 



J. By recombinations of genes, there may be produced 

 in some of the descendants characteristics that had not 

 before occurred. 



What this signifies will best be brought out by a concrete 

 case, a case described by Bateson.^ Two varieties of prim- 

 roses were crossed, one having red flowers, the other white 

 flowers. Among the descendants in later generations there 

 appeared flowers of many different colors: white, slightly 

 tinged, pink, magenta, various shades of red. Some of the 

 descendants had flowers blotched in the center, a condition 

 not found in the parents. In place of two colors there were 

 a dozen or more, present in diverse stocks. Also, some of 

 the descendants differed in the form of the flower parts and 

 in their size from the condition in either original parent. 

 A large number of diverse color and shape characteristics 

 have been brought into existence. 



Similar relations are illustrated in the extensive work of 

 Baur in crossing two varieties of Antirrhinum,^ the snap- 

 dragon. The two parent stocks differed in size, shape and 

 color of the flowers: one had yellowish white flowers, the 

 other deep red. Their progeny in Fi were as usual uniform 



