

CHAP. IX. SELF-FERTILE VARIETIES. 349 



four generations. It should however be remembered 

 that seedlings raised from this variety, when crossed by 

 a fresh stock, were wonderfully superior in height and 

 fertility to the self-fertilised plants of the corresponding 

 generation. 



Secondly, in the sixth self-fertilised generation of 

 Ipomoea a single plant named the Hero appeared, which 

 exceeded by a little in height its intercrossed opponent, 

 a case which had not occurred in any previous 

 generation. Hero transmitted the peculiar colour of 

 its flowers, as well as its increased tallness and a high 

 degree of self-fertility, to its children, grandchildren, 

 and great-grandchildren. The self-fertilised children 

 of Hero were in height to other self-fertilised plants 

 of the same stock as 100 to 85. Ten self-fertilised 

 capsules produced by the grandchildren contained on 

 an average 5 '2 seeds; and this is a higher average 

 than was yielded in any other generation by the 

 capsules of self-fertilised flowers. The great-grand- 

 children of Hero derived from a cross with a fresh 

 stock were so unhealthy, from having been grown at 

 an unfavourable season, that their average height in 

 comparison with that of the self-fertilised plants 

 cannot be judged of with any safety ; but it did not 

 appear that they had profited even by a cross of this 

 kind. 



Thirdly, the plants of Nicotiana on which I experi- 

 mented appear to come under the present class of 

 cases ; for they varied in their sexual constitution 

 and were more or less highly self-fertile. They 

 were probably the offspring of plants which had been 

 spontaneously self-fertilised under glass for several 

 generations in this country. The flowers on the 

 parent-plants which were first fertilised by me with their 

 own pollen yielded half again as many seeds as did 



