178 



GENERAL BOTANY 



sown on opposite sides of two large pots, but only four pairs came 

 up at the same time. The pots were kept in the greenhouse. The 

 seedlings of both lots when between six and seven inches in height 

 were equal. When nearly full grown they were measured as in the 

 following table : 



PI SUM 'SATIVUM 



The average height of the four crossed plants is here 34.62, and 

 that of the four self-fertilized plants 39.68, or as 100 to 115. So the 

 crossed plants, far from beating the self-fertilized, were completely 



beaten by them. 



Conclusions. The first and 

 most important of the conclu- 

 sions which may be drawn from 

 the observations given in this 

 volume is that cross-fertilization 

 is generally beneficial and self- 

 fertilization is injurious. This 

 is shown by the differences in 

 height, weight, constitutional 

 vigor, and fertility of the off- 

 spring from crossed and self- 

 fertilized flowers, and in the 

 number of seeds produced by 

 the parent plants. 



FIG. 91. Increased vigor due to 

 crossing in corn 



The two small ears at the right and left 

 represent two pure strains of corn derived 

 hy continued self-pollination and self- 

 fertilization; the middle ear represents 

 the first-generation hybrid, derived hy 

 crossing the two strains. After East 



Darwin's early experiments 

 were in many instances some- 

 what faulty, but his conclu- 

 sions have been found to 

 be in the main correct for 



