ON BIASTREPSIS IN ITS RELATION TO CULTIVATION. 159 



It is of importance to remark that the number of twisted indivi- 

 duals had increased, with the larger space, not merely relatively in 

 percentage but absolutely per square metre. In the third generation 

 there were fifty plants to the square metre of which 4 per cent. 

 (1-7 per cent.), or about 1^ plants, were twisted: in the fourth 

 generation I had four square metres with thirty-seven twisted indi- 

 viduals, that is, about nine to the square metre. 



I selected from this bed the seven best plants as seed-bearers, 

 all of them having local biastrepsis in some of the branches, and 

 I isolated them before flowering. 



The fifth generation, 1893-4, gave less favourable results: it yielded 

 only 20 per cent, of twisted main stems. In this case I had not, as 

 previously done, sown the seed on the beds, but in pans standing 

 in the greenhouse of my laboratory. This method has since proved 

 itself to be the more convenient and certain and it was adopted 

 with both the succeeding generations. 



The seed harvested in September 1892 was sown in the middle 

 of March 1893. About the middle of April the best seedlings were 

 transplanted singly into 10 cm. pots, containing well-manured loam; 

 and about the middle of May they were planted out in the beds at 

 about the same distance from each other as in the previous experi- 

 ment (twenty- two plants to the square metre). In the next year 

 all the shoots shot up and, on counting them, the following results 

 were obtained: — 



A and B are two groups of plants grown from seeds specially 

 collected from two of the 1892 seed-bearers. 



The number of plants is obviously too small to admit of attaching 

 much importance to the percentages obtained. 



In the autumn of 1894 the seed of the four best plants, which had 

 been isolated from the rest, was harvested. 



The sixth generation, 1895-6, yielded a much more satisfactory 

 result, viz. 42 per cent, of individuals with twisted main stems; a 

 result which was due, in part at least, to the greater distance of the 

 plants from each other, the other conditions of cultivation being as 

 before. The seed of 1894 was sown about the middle of March 1895 



