272 SUMMARY OF MEASUREMENTS. CHAP. VII. 



be crossed with intercrossed plants of the same stock 

 with little or no advantage, although they profited to 

 an extraordinary degree by a cross with a fresh stock. 



With respect to the greater number of the plants 

 in Table A, nothing special need here be said ; full 

 particulars may be found under the head of each 

 species by the aid of the Index. The figures in the 

 right-hand column show the mean height of the self- 

 fertilised plants, that of the crossed plants with which 

 they competed being represented by 100. No notice 

 is here taken of the few cases in which crossed and 

 self-fertilised plants were grown in the open ground, 

 so as not to compete together. The table includes, 

 as we have seen, plants belonging to fifty-four species, 

 but as some of these were measured during several 

 successive generations, there are eighty-three cases in 

 which crossed and self-fertilised plants were compared. 

 As in each generation the number of plants which 

 were measured (given in the table) was never very large 

 and sometimes small, whenever in the right-hand 

 column the mean height of the crossed and self-fertilised 

 plants is the same within five per cent., their heights 

 may be considered as practically equal. Of such cases, 

 that is, of self-fertilised plants of which the mean 

 height is expressed by figures between 95 and 105, 

 there are eighteen, either in some one or all the gene- 

 rations. There are eight cases in which the self- 

 fertilised plants exceed the crossed by above five per 

 cent., as shown by the figures in the right-hand column 

 being above 105. Lastly, there are fifty-seven cases 

 in which the crossed plants exceed the self-fertilised in 

 a ratio of at least 100 to 95, and generally in a much 

 higher degree. 



If the relative heights of the crossed and self-fertilised 

 plants had been due to mere chance, there would have 



