262 SUMMARY OF MEASUREMENTS. CHAP. VII. 



plants of the second self-fertilised generation were 

 crossed with pollen from a plant of the same variety 

 brought from a distant garden, and other flowers were 

 again self-fertilised. Plants derived from a cross with 

 a fresh stock and plants of the third self-fertilised 

 generation were thus raised. The former were to 

 the self-fertilised in weight as 100 to 22 ; and this 

 enormous difference must be attributed in part to 

 the beneficial effects of a cross with a fresh stock, 

 and in part to the deteriorating effects of self-fertilisa- 

 tion continued during three generations. 



(4.) Iberis umbellata. Seedlings from a crimson 

 English variety crossed by a pale-coloured variety 

 which had been grown for some generations in Algiers, 

 were to the self-fertilised seedlings from the crimson 

 variety in height as 100 to 89, and as 100 to 75 in 

 fertility. I am surprised that this cross with another 

 variety did not produce a still more strongly marked 

 beneficial effect ; for some intercrossed plants of the 

 crimson English variety, put into competition with 

 plants of the same variety self-fertilised during three 

 generations, were in height as 100 to 86, and in 

 fertility as 100 to 75. The slightly greater difference 

 in height in this latter case, may possibly be attributed 

 to the deteriorating effects of self-fertilisation carried 

 on for two additional generations. 



(5.) Eschsclioltzia calif ornica. This plant offers an 

 almost unique case, inasmuch as the good effects of a 

 cross or the evil effects of self-fertilisation are confined 

 to the reproductive system. Intercrossed and self- 

 fertilised plants of the English stock did not differ 

 in height (nor in weight, as far as was ascertained,) in 

 any constant manner ; the self-fertilised plants usually 

 having the advantage. So it was with the offspring 

 of plants of the Brazilian stock, tried in the same 



