CHAP. VII. TABLE A. 279 



self-fertile, and were never seen to be visited by insects in the 

 hothouse, so as to be crossed by them. This plant, moreover, 

 has been cultivated under glass for several generations in pots, 

 and therefore under nearly uniform conditions. The capsules 

 produced by the cross-fertilised flowers on the above thirty-four 

 crossed plants contained more seeds than did the capsules 

 produced by the self-fertilised flowers on the self-fertilised plants, 

 in the proportion of 100 to 85 ; so that in this respect crossing 

 was beneficial. 



(23.) Primula, sinensis. The offspring of plants, some of 

 which were legitimately and others illegitimately fertilised with 

 pollen from a distinct plant, were almost exactly of the same 

 height as the offspring of self-fertilised plants ; but the former 

 with rare exceptions flowered before the latter. I have shown 

 in my work on heterostyled plants that this species is commonly 

 raised in England from self-fertilised seed, and the plants from 

 having been cultivated in pots have been subjected to nearly 

 uniform conditions. Moreover, many of them are now varying 

 and changing their character, so as to become in a greater or 

 less degree equal-styled, and in consequence highly self-fertile. 

 Therefore I believe that the cause of the crossed plants not 

 exceeding in height the self-fertilised is the same as in the two 

 previous cases of Pisum sativum and Canna. 



(24, 25, 26.) Nicotiana tabacum.Fonr sets of measurements 

 were made ; in one, the self-fertilised plants greatly exceeded in 

 height the crossed, in two others they were approximately equal 

 to the crossed, and in the fourth were beaten by them ; but this 

 latter case does not here concern us. The individual plants 

 differ in constitution, so that the descendants of some profit by 

 their parents having been intercrossed, whilst others do not 

 Taking all three generations together, the twenty-seven crossed 

 plants were in height to the twenty-seven self-fertib'sed plants 

 as 100 to 96. This excess of height in the crossed plants is so 

 small compared with that displayed by the offspring from the 

 same mother-plants when crossed by a slightly different variety, 

 that we may suspect (as explained under Table C) that most of 

 the individuals belonging to the variety which served as the 

 mother-plants in my experiments, had acquired a nearly similar 

 constitution, so as not to profit by being mutually intercrossed. 



Reviewing these twenty-six cases, in which the 

 crossed plants either do not exceed the self-fertilised 



