CONTRACTILE FILAMENTS OF AGARICULS MUSCARIA. 79 



for they seemed to show very clearly that the contraction is 

 not due to a mechanical withdrawal of water. The following 

 experiments also point to the same conclusion: — 10.5 a.m. 

 irrigated a preparation with 1 per cent, solution of cafi'ein 

 with no eft'ect; at 10.11 added a drop of 1 per cent, nicotin 

 solution, and instantly the filament contracted. Nicotin does 

 not seem to be a simple poison, but to cause much excitement in 

 the filaments. For in another ex})eriment irrigation with 1 per 

 cent, solution produced rapid shooting out of filaments followed by 

 contraction and writhing movements ; ultimately the filaments 

 became transparent as if treated with ammonia. The same effect 

 of nicotin was again obtained in another case. These results 

 agree with the effects of thein and nicotin observed by my father 

 on Drosera.^ 



In this connection it is worth giving tlie results of some com- 

 parative experiments made with thymol and carbolic acid on the 

 filaments of Dipsacus. 



Thymol. — I am indebted to the kindness of Dr. Burdon Sander- 

 son for some of this substance. It is extremely fatal to low organ- 

 isms, being said to be about 200 times as poisonous to bacteria as 

 carbolic acid. It is easily dissolved by adding a trace of alcohol 

 to the water used for the solution. A centigram accurately 

 weighed was dissolved in '39 gram absolute alcohol ; it was 

 then made up to 10 c.c. with distilled water and a little alcohol. 

 Its strength was nearly ^V P^r cent, thymol and 10 per cent, 

 alcohol. As a control solution 1 per cent, (by bulk) of absolute 

 alcohol was used. 11.50 a.m., irrigated with 10 per cent, alcohol, 

 which produced no effect; 11.55, irrigated with ,V per cent, 

 thymol; 11. 55^, contraction of filament. A similar experiment gives 

 the same result. I subsequently mounted specimens in 10 per cent, 

 solution of absolute alcohol and plenty of filaments were pro- 

 truded. My father has shown- that dilute spirit of wine is not 

 poisonous to Drosera. 



The above thymol solution was diluted with an equal bulk of 

 water and used to irrigate two preparations, in both which it caused 

 the filaments to contract. The poison was here present in the 

 proportion of 1 to 2000. On another occasion a solution contain- 

 ing tV per ceii*^- thymol and 4 per cent, alcohol was prepared. 

 The above experiment of irrigating thoroughly with control solu- 

 tion of 10 per cent, absolute alcohol, and then substituting the 

 thymol solution, was repeated with the same results. In many 

 of the later experiments contraction did not take place nearly 

 so rapidly — not till irrigation with thymol had been continued for 

 several minutes. 



' 'Insectivorous Plants,' p. 203-4. 

 2 Ibid., p. 78. 



