CHAP. VIII. FLOWERS ON THE SAME PLANT. 303 



exposed to different conditions, or to their having 

 varied from unknown causes in a manner which we in 

 our ignorance are forced to speak of as spontaneous. 

 Hereafter I shall have to recur to this subject of the 

 inefficiency of a cross between the flowers on the same 

 plant, when we consider the part which insects play in 

 the cross-fertilisation of flowers. 



On the Transmission of the good Effects from a Cross 

 and of the evil Effects from Self-fertilisation. We have 

 seen that seedlings from a cross between distinct plants 

 almost always exceed their self-fertilised opponents in 

 height, weight, and constitutional vigour, and, as will 

 hereafter be shown, often in fertility. To ascertain 

 whether this superiority would be transmitted beyond 

 the first generation, seedlings were raised on three 

 occasions from crossed and self-fertilised plants, both 

 sets being fertilised in the same manner, and therefore 

 not as in the many cases given in Tables A, B, and C, 

 in which the crossed plants were again crossed and the 

 self-fertilised again self-fertilised. 



Firstly, seedlings were raised from self-fertilised 

 seeds produced under a net by crossed and self-fer- 

 tilised plants of Nemophila insignis; and the latter 

 were to the former in height as 133 to 100. But these 

 seedlings became very unhealthy early in life, and grew 

 so unequally that in both lots some were five times 

 as tall as the others. Therefore this experiment was 

 quite worthless ; but I have felt bound to give it, as 

 opposed to my general conclusion. I should state that 

 in this and the two following trials, both sets of plants 

 were grown on the opposite sides of the same pots, and 

 treated in all respects alike. The details of the experi- 

 ments may be found under the head of each species. 



Secondly, a crossed and a self-fertilised plant of 

 Heartsease (Viola tricolor) grew near together in the 



