382 OLDENBUSCH: STIMULATION OF PLANTS 
growth is not as great as normal in these dilutions. Although 
the M/4,000 and M/2,000 solutions do not entirely inhibit 
growth, they do retard it below normal. Complete inhibition 
was found in the saturated CS, solution, but no dilutions were 
tried between that and the above. 
Koch (18) tried similar experiments with Helianthus annuus 
and Cucurbita Pepo seeds, letting the seeds germinate and then 
placing them inthe dark, with their hypocotyls in solutions 
containing 0.1 and 0.05 cc. CS, to 1000 cc. water for thirteen 
to fourteen hours. In one case only, in the solution containing 
0.05 cc. CS2 to the liter(about M/150 solution), did he obtain 
growth higher than normal. This being only a single instance 
was probably an accident due to the solution being weaker 
than intended and cannot in any sense be called a stimulation. 
Koch did not try any solutions weaker than this and therefore 
did not reach the stimulatory region but really only determined 
that carbon disulphide acted as an inhibitory agent. 
2. STIMULATION OF DORMANT TWIGS 
Johannsen (16), investigating the effect of ether on dormant 
twigs, found that they were stimulated so that the buds opened 
sooner and developed more rapidly when exposed to ether vapor 
for twenty-four to forty-eight hours, than when unexposed. 
When using chloroform a much smaller amount was_neces- 
sary to produce the same result (9 grams of chloroform giv- 
ing the same acceleration as 40 grams of ether). 
With these results in view, experiments were carried out to 
see if vaporized carbon disulphide would stimulate buds to open. 
Willow twigs were cut from trees outdoors which had been 
subjected to winter conditions and were probably frozen in 
spite of the general mildness of the winter. The lower three or 
four inches of the stem were placed in a bottle of water and a 
large bell-jar put over them. Pieces of filter paper, moistened 
with 10 cc. of carbon disulphide were quickly inserted under the 
bell-jar. The whole was placed in a pan of water making a 
water seal so that the carbon disulphide, which vaporizes almost 
immediately, could not escape from the bell-jar. The twigs 
left in this atmosphere (approximately saturated with CS; 
gas) for periods ranging from ten minutes to eighteen hours. 
They were then removed, the stems were put into fresh water 
and with a control placed in the greenhouse. 
