ALKALOIDS 83 



A 10 per cent, solution produces an immediate cessation of streaming 

 in both cases, and the leaf-cells show signs of death within half an hour. 

 If irrigated with 2 per cent. Atropin as soon as streaming has ceased, 

 it begins again in three to five minutes, but the same effect is also 

 produced after a somewhat longer interval if 2 per cent. Muscarin is used. 

 Hence it is merely due to the dilution of the concentrated solution. 

 Ten per cent, solution usually causes slight plasmolysis, but 5 to 6 per cent, 

 solutions produce a similar stoppage without any perceptible retraction 

 of the protoplast. Nevertheless, an amount of water may have been 

 withdrawn corresponding to the elastic contraction of the stretched cell- 

 wall, and in any case the influence of suddenly applied strong solutions 

 is physical rather than chemical. 



Dilute solutions of Curare gave in general similar results, but this 

 substance appears to be more distinctly poisonous to plants than Muscarin, 

 Atropin, or Veratrin. No precise determinations were, however, possible, 

 the available supply of this poison being very limited. 



Eserin sulphate yields closely corresponding results to those given by 

 Muscarin, and here also sudden immersal in strong solutions (2 per cent.) 

 produces effects which are not shown when the solution is applied in 

 slowly increasing concentration. 



If streaming in Chara or Nitella is stopped by a solution of Eserin, 

 and dilute Atropin added as it recommences, frequently a slight temporary 

 acceleration occurs followed in a few minutes by a retardation or tem- 

 porary cessation. If the Eserin is removed by water and Atropin added 

 when streaming is active again, the usual shock-stoppage is produced, 

 but the latent period of recovery is shorter than before. 



Atropin resembles Muscarin in its general action, but is even less 

 poisonous. Thus a plant of Elodea remained living for three weeks 

 although kept in a sterile 2 per cent, solution of Atropin renewed every 

 two or three days. 



Cells of Nitella and Chara may remain living and showing fairly active 

 streaming from four to seven days in solutions containing 0-5 per cent. 

 Atropin and 0-5 per cent. Muscarin, whereas in i per cent, solutions 

 of either of these substances, the cells are usually killed within two to 

 four days. This does not indicate any such antagonism as is shown 

 when these poisons act simultaneously upon the nervous mechanism of 

 the Vertebrate heart, for plants may withstand the action of various 

 poisons when applied conjointly, each in half the lethal concentration. 



Veratrin^ is insoluble in water, but dissolves readily in alcohol. 

 By dilution with water, solutions may be obtained containing i per cent, 

 of Veratrin and 2 to 3 per cent, of alcohol. Such a solution causes the 



1 Obtained pure from Merck of Darmstadt. 

 G 2 



