204 NICOTIANA TABACUM. CHAP. VL 



approximately equal ; and in one (i.e., in the first generation) 

 the self-fertilised plants were greatly superior to the crossed. 

 In no case did the capsules from flowers fertilised with pollen 

 from a distinct plant yield many more, and sometimes they yielded 

 much fewer seeds than the capsules from self-fertilised flowers. 

 But when the flowers of one variety were crossed with pollen 

 from a slightly different variety, which had grown under 

 somewhat different conditions, that is, by a fresh stock, the 

 seedlings derived from this cross exceeded in height and weight 

 those from the self-fertilised flowers in an extraordinary degree. 

 Twelve flowers on some plants of the common tobacco, raised 

 from purchased seeds, were crossed with pollen from a distinct 

 plant of the same lot, and these produced ten capsules. Twelve 

 flowers on the same plants were fertilised with their own pollen, 

 and produced eleven capsules. The seeds in the ten crossed 

 capsules weighed 31 '7 grains, whilst those in ten of the self- 

 fertilised capsules weighed 47 '67 grains; or as 100 to 150. The 

 much greater productiveness of the self-fertilised than of the 

 crossed capsules can hardly be attributed to chance, as all the 

 capsules of both lots were very fine and healthy ones. 



The seeds were placed on sand, and several pairs in an equal 

 state of germination were planted on the opposite sides of three 

 pots. The remaining seeds were thickly sown on the two sides 

 of Pot IV., so that the plants in this pot were much crowded. 

 The tallest plant on each side of each pot was measured. Whilst 

 the plants were quite young the four tallest crossed plants 

 averaged 7 -87 inches, and the four tallest self-fertilised 14 '87 

 inches in height ; or as 100 to 189. The heights at this age are 

 given in the two left-hand columns of the following table. 



When in full flower the tallest plants on each side were again 

 measured (see the two right-hand columns), with the following 

 result. But I should state that the pots were not large enough, 

 and the plants never grew to their proper height. The four 

 tallest crossed plants now averaged 18 -5, and the four tallest 

 self-fertilised plants 32 -75 inches in height; or as 100 to 178. 

 In all four pots a self-fertilised plant flowered before any one of 

 the crossed. 



In Pot IV., in which the plants were extremely crowded, the 

 two lots were at first equal ; and ultimately the tallest crossed 

 plant exceeded by a trifle the tallest self-fertilised plant. This 

 recalled to my mind an analogous case in the one generation of 

 Petunia, in which the self-fertilised plants were throughout 



