536 Heritable Spiral Torsions. 



importance, inasmuch as it determines the length of the 

 life of the plant up to the moment of the production of 

 the stem. The longer this period continues under favor- 

 able circumstances the greater is the likelihood of the 

 leaves becoming spirally arranged. 



Sowings, made in summer or early autumn, which 

 gave rise to stems in the next year, reduced the prospect 

 of obtaining- torsions almost to nil. On the other hand, 

 autumn sowings which do not give rise to stems until 

 the summer after the next, contam very large numbers 

 of twisted specimens; so that if the seeds are sown late 

 in the autumn the proportion of plants with a spiral ar- 

 rangement of their leaves is even greater than amongst 

 plants raised from seeds sown in th« spring. 



Little effect is produced upon the result of a culture 

 by sowing in March or in April or even in the begin- 

 ning of May. Also it does not matter much whether 

 the sowing is carried out in the greenhouse in pans and 

 the seedlings planted out later into the beds, or whether 

 the seeds are sown where they are to grow. For various 

 reasons I have for many years preferred the former 

 method, as it is more convenient and safer, especially in 

 dry springs. 



A good loose soil with a strong manure rich in nitrates 

 seems to be an essential condition. On unmanured sandy 

 soil even the best seeds do not produce twisted individuals, 

 and on hard or barren soil the proportion is considerably 

 diminished. 



It is possible to confine the cycle of life of Dipsactis 

 sylvestris tarsus within the limits of a year by sowing 

 the seeds under favorable circumstances immediately 

 after they are ripe. In this way a generation can be 

 grown every year, and an annual twisted race might pos- 



