622 



PRACTICAL PROBLEMS 



On this point compare the facts reported in the following 

 table for the fourth generation. 1 



Here again each inbred plant is inferior to its particular mate, 

 but only three of the cross-breds equaled the best inbred plant 



of the series (80 inches), and 

 all but one of the inbreds were 

 more vigorous than the poor- 

 est cross-bred. 



The same general fact is 

 noticeable in the next (fifth) 

 generation, though not quite 

 so pronounced, except that in 

 one case the inbred plant 

 equaled its own mate. Evi- 

 dently something was prepar- 

 ing to happen. 



The appearance of " Hero." In the next (sixth) generation 

 there appeared a specially vigorous plant that overtopped its own 

 competitor by half an inch and exceeded in height all but three 

 of the series. Darwin named this plant " Hero," and remarks, 

 " I was so much surprised at this fact that I resolved to ascertain 

 whether this plant would transmit its powers of growth to its 

 seedlings." 



Accordingly he fertilized a number of flowers of Hero with 

 their own pollen, and planted the seedlings in competition with 

 other inbred plants and with cross-bred as well. The two tables 

 on the next page show how the descendants of Hero acquitted 

 themselves. 



Here, then, out of a species sensitive to inbreeding, has arisen 

 a plant that is strong, vigorous, and prolific, and its own inbred 

 seedlings at once demonstrate their superiority not only to other 

 inbred stock but also to their crossed competitors. As Darwin 

 remarks, 2 " Hero transmitted to its offspring a peculiar consti- 

 tution adapted for self-fertilization"; and again, 3 "It appears, 

 therefore, that Hero and its descendants have varied from the 

 common type not only in acquiring great power of growth and 



1 Darwin, Cross and Self Fertilization, etc., p. 34. 



2 Ibid. p. 50. 3 Ibid. 51. 



