Relation to Cultivation. 
405 
touch nor overshadow each other. This result is clearly 
indicated by the various cultures previously described. 
It is instructive, in connexion with this point, to compare 
the plants growing on the borders of a bed with those growing 
in the middle. Whenever the space becomes insufficient, the 
twisted stems are mostly or even entirely confined to the 
plants growing on the borders : this was the case in the 
second and third generations, when there were about fifty 
plants to the square metre. On the other hand, the occurrence 
of spiral rosettes in the plants on the borders, and the absence 
of them from those in the middle of the bed, is one of the 
best indications whether or not the plants have sufficient 
space allotted to them. 
In order to demonstrate in a simple manner the truth of 
the above statement, I instituted the following experiments. 
In 1889 seeds, obtained from the second generation in 
1887, were sown on two neighbouring beds and in the same 
manner. When, in June, the plants began to touch each 
other, they were not thinned out to an equal extent ; on the 
one bed 300 plants were left, on the other 540. As each bed 
had an area of twelve square metres, there were in the one 
case twenty-five plants to the square metre, in the other forty- 
five. On examining the elongated shoots in May of the 
following year the results, which were widely different in the 
two cases, were — 
Bed, 25 plants to square metre 6% twisted stems. 
„ „ 5% phyllotaxis 
Bed, 45 plants to square metre 1% twisted stems. 
„ „ 1 % phyllotaxis 
I made a second experiment, in which the plants were still 
more crowded together. In the first summer I allowed 136 
plants to grow on a bed of s-i square metres area, that is, 
sixty-five plants to the square metre. In order to eliminate 
the effect of the border-position, I surrounded the bed with 
a margin of plants placed about as closely as the others, but 
these marginal plants were not subsequently counted in with 
the others. When I examined the rosettes in the following 
