Hybridization 115 



per cent more vigorous than crosses between plants grown 

 side by side for some time and over 44 per cent more 

 vigorous than plants from self-fertilized seeds. On the 

 other hand, experiments showed that crosses between 

 different flowers on the same plant gave actually poorer 

 results than offspring of self -fertilized flowers. It is 

 evident, from all of these figures, that nature desires 

 crosses between plants, and, if possible, between plants 

 grown under somewhat different conditions. All these 

 results are exceedingly interesting and important ; and 

 there is every reason to believe that, as a rule, similar 

 results can be obtained with all plants. 



Darwin's results with other plants. Darwin extended 

 his investigation to many plants, only a few of which need 

 be discussed here. Cabbage gave pronounced results. 

 Crossed plants were to self-fertilized plants in weight as 

 100 is to 37. A cross was now made between these crossed 

 plants and a plant of the same variety from another 

 garden, and the difference in weight of the resulting off- 

 spring was the difference between 100 and 22, showing a 

 gain of over 350 per cent, due to a cross with fresh stock. 

 Crossed lettuce plants exceeded uncrossed in height as 

 100 exceeds 82. Buckwheat gave an increase in weight 

 of seeds as 100 to 82, and in height of plants as 100 to 69. 

 Beets gave an increase in height represented by 100 to 87. 

 Maize, when full grown, from crossed and uncrossed seeds, 

 gave the difference in height between 100 and 91. Canary 

 grass gave similar results. 



Increased vigor in other crosses. Results as well 

 marked as these have been secured on a large and what 

 might be called a commercial scale. The first gen- 



