CHAP. VII. TABLE C. 257 



source of some diversity of constitution will have been 

 wholly eliminated ; and the sexual elements produced 

 by the same flower must have been developed under as 

 nearly the same conditions as it is possible to conceive. 



In Table C the crossed plants are the offspring of a 

 cross with a fresh stock, or with a distinct variety ; and 

 they were put into competition either with self-fertilised 

 plants, or with intercrossed plants of the same old stock. 

 By the term fresh stock I mean a non-related plant, 

 the progenitors of which have been raised during some 

 generations in another garden, and have consequently 

 been exposed to somewhat different conditions. In the 

 case of Nicotiana, Iberis, the red variety of Primula, the 

 common Pea, and perhaps Anagallis, the plants which 

 were crossed may be ranked as distinct varieties or 

 sub-varieties of the same species ; but with Ipomoea, 

 Mimulus, Dianthus, and Petunia, the plants which 

 were crossed differed exclusively in the tint of their 

 flowers ; and as a large proportion of the plants raised 

 from the same lot of purchased seeds thus varied, the 

 differences may be estimated as merely individual. 

 Having made these preliminary remarks, we will now 

 consider in detail the several cases given in Table C, 

 and they are well worthy of full consideration. 



(1.) Ipomoea purpurea. Plants growing in the same 

 pots, and subjected in each generation to the same 

 conditions, were intercrossed for nine consecutive 

 generations. These intercrossed plants thus became in 

 the later generations more or less closely inter-related. 

 Flowers on the plants of the ninth intercrossed genera- 

 tion were fertilised with pollen taken from a fresh 

 stock, and seedlings thus raised. Other flowers on the 

 same intercrossed plants were fertilised with pollen 

 from another intercrossed plant, producing seedlings of 

 the tenth intercrossed generation. These two sets of 



