22-2 REVIEWS. 



others a less good showing for the advantage of cross-fertili- 

 zation, and this advantage manifesting itself in different 

 ways, some in vigor or amount of growth, some in hardiness, 

 most in fertility ; but with twelve cases in which the crossed 

 plants showed no marked advantage over the self-fertilized. 

 There were, however, fifty-seven cases in which the crossed 

 exceeded the self-fertilized by at least five per cent., gener- 

 ally by much more. 



Increase of vigor, as evinced in growth, appears generally 

 to be accompanied by increased fertility ; but sometimes the 

 good of crossing was manifested only in productiveness, i. e., 

 in a larger amount of seed. This proved to be the case in 

 Eschscholtzia, in which — strange to say — self -fertilized plants 

 of several generations were superior in size and weight to 

 intercrossed plants, even when the crossing was between 

 flowers derived on one side from American, on the other 

 from English seed, from which, upon Mr. Darwin's view, the 

 maximum benefit should be gained. This instance, however, 

 stands alone. Yet it is approached by several others, in a 

 manner which might have negatived the general conclusions 

 of the research, if they had been hastily gathered from a 

 small number of trials. 



For example, in the sixth self-fertilized generation of Ipo- 

 mcea purpurea, one of these plants took the lead of its com- 

 petitor, kept it almost to the end, and was ultimately over- 

 topped only by half an inch on a total height of several feet. 

 To ascertain whether this exceptionally vigorous plant would 

 transmit its power to its seedlings, several of its flowers were 

 fertilized with their own pollen, and the seedlings thus raised 

 were put into competition with ordinary self-fertilized and 

 with intercrossed plants of the corresponding generation. 

 The six children of Hero (the name by which, this individual 

 was designated) beat the ordinary self-fertilized competitors 

 at the rate of 100 to 84, and the intercrossed competitors at 

 the rate of 100 to 95 ; and in the next generation the self- 

 fertilized grandchildren beat those from a cross between two 

 of the children at the rate of 100 to 94. In the next genera- 

 tions the seedlings were raised in winter in a hot-house, became 



