CiiAr. 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 



s 



