450 REPRODUCTION. 



1154. "All the self-fertilized plants of the seventh genera- 

 tion, and I believe of one or two previous generations, produced 

 flowers of exactl3- the same tint ; namel}', of a rich dark pur- 

 ple. So did all the plants, without any exception, in the three 

 succeeding generations of self-fertilized plants ; and very many 

 were raised on account of other experiments in progress not 

 here recorded. . . . The flowers were as uniform in tint as 

 those of a wild species growing in a state of nature. . . . 

 The crossed plants continued to the tenth generation to vary 

 in the same manner as before, but to a much less degree, 

 owing probably to their having become more or less closely 

 inter-related." ■'■ 



1155. In the sixth self-fertilized generation there appeared a 

 plant which was larger than its crossed competitor, and its pow- 

 ers of growth and fertility were transmitted to its descendants. 

 Thus it appears that even with the exclusion of foreign pollen 

 new characters can assert themselves. 



1156. It was not found in these experiments that simply cross- 

 ing a flower from another flower on the same plant was produc- 

 tive of an}' advantage ; on the contrar}-, there are some cases 

 which show that it may result in an actual disadvantage. " The 

 benefits which so generally follow from a cross between two 



Third generation of crosned and self-fertilized plants. Crossed capsules com- 

 pared with self-fertilized capsules yielded seeds in the ratio of . 100 to 94. 



An eq^ual number of crossed and self-fertilized plants, both spontaneonsly 

 self-fertilized, produced capsules in the ratio of 100 to 38. And these capsules 

 contained seeds in the ratio of 100 to 94. Combining these data, the produc- 

 tiveness of the crossed to the self-fertilized plants, both spontaneously self- 

 fertilized, was as 100 to 35. 



Fourth generation of crossed and self-fertilized plants. Capsules from flow- 

 ers on the crossed plants fertilized by pollen from another plant, and capsules 

 from flowers on the self-fertilized plants feitilized with their own pollen, con- 

 tained seeds in the proportion of 100 to 94. 



Fifth generation of crossed and self-fertilized plants. The crossed plants 

 produced spontaneously a vast number more pods (not actually counted) than 

 the self-fertilized, and these contained seeds in the proportion of 100 to 89. 



Ninth generation of crossed and self-fertilized plants. Fourteen crossed 

 jiknts spontaneously self-fertilized, and fourteen self-fertilized plants sponta- 

 neously self-fertilized, yielded capsules (the average number of seeds per capsule 

 not having been ascertained) in the proportion of 100 to 26. 



Plants derived from a cross with a fresh stock compared with intercrossed 

 plants. The offspring of intercrossed plants of the ninth generation, crossed 

 by a fresh stock, compared with plants of the same stock intercrossed during 

 ten generations, both sets of plants left uncovered and naturally fertilized, 

 produced capsules by weight as jqO ^^ -j 



1 Darwin : Effects of Cross and Self Fertilization, p. 59. 



