14 



riot yet had an opportunity of verifying the correctness of 

 these statements. 



A very interesting series of observations has been insti- 

 tuted on the effects on the circulation of the sap in Chara of 

 chemical substances, whose actions on the excitability of ani- 

 mals are known. A portion of a Chara was placed in a solu- 

 tion of caustic potash, containing about ^innr f tms substance; 

 the motion at first became slow, but five minutes afterwards 

 it was again very strong. After twenty-five minutes the mo- 

 tion again became slower, and in thirty-five minutes entirely 

 ceased. Lime-water increased the motion in the cells of Chara 

 in from two to three minutes : this remarkable result I am 

 able to confirm. Momentary immersion of the Charce in lime- 

 water did them no harm, but if suffered to remain in it from 

 four to five minutes the circulation ceased. In a solution of 

 tartaric acid (1 part to 50 of \vater) the circulation continued 

 in the cells for ten or twelve minutes only ; in a weaker solu- 

 tion of this acid (1 to 1000 water) the motion became very slow; 

 but five minutes afterwards it regained its activity by the re- 

 action of the vital forces. After three quarters of an hour the 

 circulation became feeble, and after one hour entirely ceased. 



A similar result was obtained with a solution of sea salt, and 

 M. Dutrochet came to the conclusion, that strong doses of 

 salts and of acids put a decided end to the circulation in Chares, 

 but that the same substances in smaller quantities causes it is 

 true a stoppage in the beginning, but that subsequently this 

 injurious action is overcome by the vital forces of the plant, 

 and the motion is to be observed afterwards as before. Mean- 

 while the case is exactly similar with the vegetative pro- 

 cesses of other plants. The motion in the cell of a Chara 

 which had been placed in a solution of extract of opium (1 part 

 to 14 of water) ceased entirely six minutes after immersion. 

 After a quarter of an hour it recommenced very slowly, but 

 after half an hour it was entirely suspended. In a weaker so- 

 lution of opium (1 part to 288 of w r ater) the effect was similar, 

 but after ten minutes the circulation again returned and con- 

 tinued, it is stated, with increased velocity for eighteen hours. 

 In a solution of opium, only half as strong, the circulation be- 

 came somewhat slower, but subsequently returned with great 

 vivacity. 



