CHAP. VI. CROSS WITH A FRESH STOCK. 201 



The ten Westerham-crossed plants here average 36 '67 inches 

 in height ; the ten intercrossed plants, 38 '27 inches ; and the ten 

 self-fertilised, 23 -31 inches. These three lots of plants were also 

 weighed ; the Westerham-crossed plants weighed 28 ounces ; the 

 intercrossed, 41 ounces; and the self-fertilised, 14 '75 ounces. 

 We thus get the following ratios : 



The Westerham-crossed plants in height to the 

 self-fertilised as 100 to 63 



The Westerham-crossed plants in weight to the 

 self-fertilised as 100 to 53 



The Westerham-crossed plants in height to the 

 intercrossed as 100 to 104 



The Westerham-crossed plants in weight to the 

 intercrossed as 100 to 146 



The intercrossed plants in height to the self- 

 fertilised as 100 to 61 



The intercrossed plants in weight to the self- 

 fertilised . . . . . . . as 100 to 36 



Here the relative heights of the three lots are nearly the same 

 (within three or four per cent.) as with the plants in the pots. 

 In weight there is a much greater difference : the Westerham- 

 crossed exceed the self-fertilised by much less than they did 

 before; but the self-fertilised plants in the pots had become 

 slightly withered, as before stated, and were in consequence 

 unfairly light. The Westerham-crossed plants are here inferior 

 in weight to the intercrossed plants in a much higher degree 

 than in the pots ; and this appeared due to their being much 

 less branched, owing to their having germinated in greater 

 numbers and consequently being much crowded. Their leaves 

 were of a brighter green than those of the intercrossed and 

 self -fertilised plants. 



Relative Fertility of the Three Lots of Plants. None of the plants 

 in pots in the greenhouse ever produced a capsule ; and this may 

 be attributed in chief part to the exclusion of moths. There- 

 fore the fertility of the three lots could be judged of only by that 

 of the plants growing out of doors, which from being left 

 uncovered were probably cross-fertilised. The plants in the 

 three rows were exactly of the same age and had been subjected 

 to closely similar conditions, so that any difference in their fer- 

 tility must be attributed to their different origin ; namely, to the 



