20 INTRODUCTORY REMARKS. CHAP. I. 



flowers on one or more of the crossed plants were ferti- 

 lised with pollen from another crossed plant of the 

 same lot. Having thus once begun, the same method 

 was followed for as many as ten successive generations 

 with some of the species. The seeds and seedlings were 

 always treated in exactly the same manner as already 

 described. The self-fertilised plants, whether originally 

 descended from one or two mother-plants, were thus in 

 each generation as closely interbred as was possible ; 

 and I could not have improved on my plan. But 

 instead of crossing one of the crossed plants with 

 another crossed plant, I ought to have crossed the self- 

 fertilised plants of each generation with pollen taken 

 from a non-related plant that is, one belonging to a 

 distinct family or stock of the same species and variety. 

 This was done in several cases as an additional experi- 

 ment, and gave very striking results. But the plan 

 usually followed was to put into competition and 

 compare intercrossed plants, which were almost always 

 the offspring of more or less closely related plants, with 

 the self-fertilised plants of each succeeding genera- 

 tion ; all having been grown under closely similar 

 conditions. I have, however, learnt more by this method 

 of proceeding, which was begun by an oversight and 

 then necessarily followed, than if I had always crossed 

 the self-fertilised plants of each succeeding generation 

 with pollen from a fresh stock. 



I have said that the crossed plants of the successive 

 generations were almost always inter-related. When 

 the flowers on an hermaphrodite plant are crossed 

 with pollen taken from a distinct plant, the seedlings 

 thus raised may be considered as hermaphrodite brothers 

 or sisters ; those raised from the same capsule being as 

 close as twins or animals of the same litter. But in 

 one sense the flowers on the same plant are distinct 



