170 ON BIASTREPSIS IN ITS RELATION TO CULTIVATION. 



ripened a fortnight earlier than with me; consequently I was able 

 to repeat the experimental sowings of the two previous years with 

 this new and favourable factor. The plants grew more rapidly than 

 those of previous years on the heated water-bath and by the middle 

 of November had formed about twice as many leaves. They were 

 kept warm until the middle of December, when they were taken 

 out and put under glass. By the end of May they had all (thirty- 

 six) thrown up their shoots, but these shoots were decussate right 

 up to the inflorescence. 



In a control-experiment made with the same seed, but without 

 artificial heat, the plants were potted off soon after germination and 

 were kept under glass in the garden: twenty-nine of them threw up 

 stems in the following year, which, as was to be expected, were 

 decussate; nine plants remained in the rosette-stage. 



The conclusion to be drawn from all these experiments is that 

 whilst it is possible to contract into one year the lifecycle of the 

 biennial Dipsacus sylvestris torsus, by sowing the seed immediately 

 it is ripe and by hurrying on germination and the early stages of 

 growth, this takes place at the cost of the biastrepsis, which is either 

 altogether wanting or is manifested in only a relatively slight degree. 



G. Cultures in other botanic gartens. 



When, in the summer of 1889, the third generation of my breed 

 began to show a distinct increase in the percentage of twisted indi- 

 viduals, I distributed seed of it for the first time; and I did so at 

 the friendly request of Professor J. Urban of the Botanic Garden at 

 Berlin. So successful was the cultivation of the breed there, that 

 in the published catalogue of the seeds gathered in 1891 there are 

 enumerated no less than five varieties of these plants with twisted 

 stems or with three-leaved whorls. Since then I have distributed seed 

 in increasing quantity, and the cultivation of the breed has been 

 successfully carried out in various Botanic Gardens, although in some 

 cases difficulties have been encountered. The plant requires not only 

 a good deal of space, open exposure and loose wellmanured soil, but 

 special attention in addition, which is often begrudged since the 

 species grows wild and is to be met with even in overgrown localities 

 and on bad soil. Carefully raised garden-plants are, however, much 

 more sensitive than wild ones, and with this the tendency to bia- 

 strepsis is intimately connected. For instance, the cultivated plants 

 are often killed by frost in damp winters with us or only the main 

 flowering shoot is killed. In the latter case lateral shoots are thrown 



