158 ON BIASTREPSIS IN ITS RELATION TO CULTIVATION. 



stem, which made their appearance among plants obtained from a 

 sowing in 1884. Before they flowered, all the other individuals had 

 been removed. From the seed of these two I obtained the second 

 generation in 1886. At that time I was unaware of the special con- 

 ditions essential to the successful cultivation of these plants and, 

 doubtless on this ground mainly, I found only two twisted indivi- 

 duals among about 1650 seedlings. Both of these flowered in iso- 

 lation and bore seed abundantly. From this seed the third gene- 

 ration was raised in 1888-9, consisting of about the same number of 

 plants, among which were sixty-seven with twisted stems, that is, 

 about 4 per cent, of the total number. The seed-bearing plants 

 selected were flowered in isolation. 



The seed for the fourth generation was sown, in part, in 1890 and 

 gave about 10 per cent, of twisted individuals, which, owing to an 

 accident, could not be used for the propagation of the breed. The 

 remainder of the 1888-9 seed was therefore sown in 1891, and, with 

 a better knowledge of the requisite conditions, I obtained 34 per cent, 

 of twisted individuals, a percentage which has been approximately 

 maintained, but not materially exceeded, in subsequent gene- 

 rations. 



The improvement in the method of cultivation was essentially 

 this, that more space was allowed to the young plants from the 

 very beginning. In the two previous generations about fifty indi- 

 viduals were grown to the square metre; in this generation the 

 number was reduced to about twenty-five by the repeated weeding- 

 out, during the month of June, of all superfluous plants so soon as 

 they began to touch one another. 



The sowing on the beds was done in the middle of May 1891. 

 At the beginning of October I found that about half a dozen plants 

 in every hundred had spiral phyllotaxis within the dense rosette; 

 and at the beginning of November I had rather more than half of 

 the plants removed as being undoubtedly normal and atavistic. 

 Towards the end of May 1892, when the shoots were being vigo- 

 rously pushed up, the plants were finally gone over and counted. 

 Including the figures for the previous November, I obtained the 

 following result for the whole sowing: — 



Twisted stems 37 = 34 % 



Stems with Vs phyllotaxis 12 = 11 % 



Normal (atavistic) 58 = 55 % 



Total 107" 



