32 



IPOMffiA PURPUEEA. 



CHAP. II. 



crossed, and from the self-fertilised plants again self-fertilised, 

 were treated in all respects exactly as before, with the following 

 result : 



TABLE HE. (Third Generation.) 



Again all the crossed plants are higher than their antagonists : 

 their average height is 77 '41 inches, whereas that of the self- 

 fertilised is 52-83 inches, or as 100 to 68. 



I attended closely to the fertility of the plants of this third 

 generation. Thirty flowers on the crossed plants were crossed 

 with pollen from other crossed plants of the same generation, 

 and the twenty-six capsules thus produced contained, on an 

 average, 4-73 seeds; whilst thirty flowers on the self-fertilised 

 plants, fertilised with the pollen from the same flower, produced 

 twenty-three capsules, each containing 4-43 seeds. Thus the 

 average number of seeds in the crossed capsules was to that in 

 the self-fertilised capsules as 100 to 94. A hundred of the 

 crossed seeds weighed 43 27 grains, whilst a hundred of the self- 

 fertilised seeds weighed only 37 63 grains . Many of these lighter 

 self-fertilised seeds placed on damp sand germinated before the 

 crossed ; thus thirty-six of the former germinated whilst only 

 thirteen of the latter or crossed seeds germinated. In Pot I. 

 the three crossed plants produced spontaneously under the net 

 (besides the twenty-six artificially cross-fertilised capsules) 

 seventy-seven self-fertilised capsules containing on an average 

 4 '41 seeds; whilst the three self-fertilised plants produced 

 spontaneously (besides the twenty-three artificially self-fertilised 

 capsules) only twenty-nine self-fertilised capsules, containing OR 

 an average 4 -14 seeds. Therefore the average number of seeds 

 in the two lots of spontaneously self-fertilised capsules was as 



