314 



FEETILITY OF CROSSED 



CHAP IX. 



number of the capsules alone. Nevertheless, in the 

 more interesting cases, the seeds were also counted 

 or weighed. The average number of seeds per capsule 

 is a more valuable criterion of fertility than the 

 number of capsules produced. This latter circum- 

 stance depends partly on the size of the plant ; and we 

 know that crossed plants are generally taller and 

 heavier than the self- fertilised ; but the difference in 

 this respect is rarely sufficient to account for the 

 difference in the number of the capsules produced. It 

 need hardly be added that in the following table the 

 same number of crossed and self-fertilised plants are 

 always compared. Subject to the foregoing sources of 

 doubt I will now give the table, in which the parentage 

 of the plants experimented on, and the manner of 

 determining their fertility are explained. Fuller 

 details may be found in the previous part of this work, 

 Tinder the head of each species. 



TABLE D. Relative Fertility of Plants of crossed and self -fertilise I 

 Parentage, loth sets being fertilised in the same manner. Fer- 

 tility judged of by various Standards. That of the crossed Plants 

 taken as 100. 



IPOM<EA PURPUREA first generation: seeds per capsule 

 on crossed and self-fertilised plants, not growing much 

 crowded, spontaneously self-fertilised under a net, in 

 number 



IPOMCEA PURPUREA seeds per capsule on crossed and 

 self-fertilised plants from the same parents as in the last 

 case, but growing much crowded, spontaneously self- 

 fertilised under a net, in number 



IPOMCEA PURPUREA productiveness of the same plants, as 

 judged by the number of capsules produced, and average 

 number of seeds per capsule 



IPOMCEA PURPUREA third generation: seeds per capsule 

 on crossed and self-fertilised plants, spontaneously self- 

 fertilised under a net, in number 



IPOMCEA PURPUREA productiveness of the same plants, 

 as judged by number of capsules produced, and ayjrage 

 number of seeds per capsule 



as 100 to 9S 



93 



45 



94 



35 



