ON PROTRUSION OF PROTOPLASMIC FILAMENTS. 255 



It is certainly poisonous to the glands and filaments of the 

 teasel ; but the latter are not excited by it as is the protoplasm 

 in the tentacles of Drosera. 



Curare. — A solution which had been used for curarizing frogs 

 was employed to irrigate preparations with ; it made the filament 

 become slightly transparent, as if effected by ammonia, but did 

 not paralyse or kill them. Curare is not poisonous to Drosera. ^ 



Cobra poison. — A solution of about \ % was used for irriga- 

 tion ; it produces a peculiar form of contraction, with an in- 

 tense wrinkling, and zig-zag appearance of little darting side 

 filaments. It is not poisonous, and the filament shoots out 

 again ; it appears to be a powerful stimulant to the filaments, 

 and this agrees with my father's observations on its extraordinary 

 exciting eff'ects on the protoplasm in the tentacles of Drosera. 



Strychnine. — A solution of 1 % of acetate of strychnine was 

 prepared, but the salt was not all dissolved, and the solution 

 used was probably "75 %. In some of the experiments, simple 

 contraction was the result. But in several instances a remark- 

 able phenomenon occurred. The filament began to contract, and 

 then suddenly became motionless, being killed in a partly 

 extended condition. The filaments were certainly dead, for they 

 could not be made to contract by subsequent irrigation with 

 strong acetic acid. This fact is important, for it shows that the 

 contraction ordinarily due to acetic acid is not a chemical effect 

 on the substance of which the filament is composed. For it is 

 extremely unlikely that both osmic acid and strychnine should 

 possess the power of hindering the chemical effect of acetic 

 acid. On the other hand, the behaviour of the filaments with 

 strychnine agrees to some extent with that of the tentacles 

 of Drosera. My father found that a solution of acetate of strych- 

 nia (stronger than \ %), when applied to tentacles which had 

 begun to move, allowed the latter to go on bending for a short 

 time, and then killed them in a semi-contracted state.^ In a 

 few cases the filaments were rendered sluggish, without being 

 killed by the strychnia solution, and a parallel effect was noted 

 by my father in Drosera. Strychnine has the same power as 

 ammonia of causing the appearance of drops of resin in the 

 epidermic cells. 



Heat.—\xx * Flora' of last year (1876, p. 177) there is a 

 careful research by Velten on the effect of heat on the streaming 

 of protoplasm. He discusses various instruments for the ex- 

 amination of microscopic objects at different temperatures. He 

 concludes that the most accurate are Sachs' heating-box (*Warm- 

 kasten'), and a modification of an apparatus of Nageli's. The 



' ' Insectivorous Plants,' p. 205. 

 2 Ibid., p. 200. 



