546 Heritable Spiral Torsions. 
time familiar with the most favorable conditions of this 
culture, and obtained only two twisted individuals amongst 
nearly 1650, probably for this reason alone. These two 
flowered in isolation and set an abundance of seed. The 
third generation (1888-1889) raised from seeds of the 
second, produced 67 twisted stems in a culture of about 
the same extent, i. e., about 4%. Here again the seed- 
parents flowered in isolation. 
The fourth generation was sown partly in 1890, and 
produced as many as 10% twisted individuals which 
however could not be used for the continuation of the 
race. The rest of the seed was sown in 1891 with a 
better knowledge of the conditions, whereby the propor- 
tion of twisted individuals rose to 34%, a value which 
the later generations on the average maintained, without 
surpassing it to any considerable extent. 
The improvement in the method of culture consisted 
essentially in providing the young plants from their very 
earliest stages with more room. In the two previous 
generations about 50 specimens were grown per square 
meter In this generation, however, the number was 
reduced to about 25 by the removal of the superfluous 
ones in June, as soon as the plants began to touch one 
another. 
The seed had been sown in May in the beds. At the 
beginning of October I noticed, amongst about 100 indi- 
viduals, 6 with a spiral arrangement of leaves in the 
heart of a rosette. In the beginning of November I was 
able to remove more than half of the plants as undoubted 
atavists, and when, towards the end of May 1892, the 
stems grew up vigorously, they were finally examined 
and recorded. The result, together with that obtained in 
November, i. e., for the whole culture, is as follows: 
