THE DETAILED ACTION OF POISONS 269 



The peculiar behaviour of Penidllium shows that generalizations as to the 

 universal poisonous action of a particular substance need to be made with extreme 

 caution. Nor is it permissible to draw conclusions from the actions of poisons 

 on dead proteids, as to their action upon the living organism which, owing to its 

 complexity, offers various points of attack. The suggestion, for instance, that a high 

 oxygen-pressure acts fatally by unduly increasing the respiratory activity is incorrect, 

 for as a matter of fact the reverse is the case. 



Various theories have been put forward to explain the primary action of 

 poisons, but these do not give any further insight into the structure and composition 

 of the protoplasm, and hence do not require discussion *. 



The power of an organism to. withstand a certain amount of poison is 

 a special instance of the property of accommodation. A plant may grow 

 in the constant presence of an infra-minimal percentage of poison just as it 

 may at temperatures below the optimum, although certain functional dis- 

 turbances are shown. Similarly recovery may be possible from supra- 

 maximal concentrations of poisons, provided the action has not been too 

 prolonged and the poison is rapidly removed again or rendered innocuous. 



In the case of substances such as ether, chloroform, alkaloids, and 

 aniline dyes, which are held loosely by the protoplasm in the form of 

 dissociating compounds, it is sufficient to place the plant in a large quantity 

 of pure water, or of air when ether and similar volatile poisons are present. 

 The protoplasm may, however, play an active part in the removal of a 

 poison by converting the poison into a diosmosing substance. This occurs 

 when the tannate of methyl blue is slowly removed from a cell in the pre- 

 sence of a trace of acid. Similarly after transitory immersal in comparatively 

 strong solutions of methyl violet and of cyanin, it can easily be seen how the 

 colouration and deformation of the cytoplasm gradually disappear again. 

 The same happens when the cell-sap accumulates the poison and withdraws 

 it from the cytoplasm 2 . This affords a good instance of the fact that a 

 poison may remain in a cell and yet be so deposited as to be harmless. 



In the root-hairs of Trianea bogotensis penetrating particles of Bismarck 

 brown combine with fragments of the cytoplasm which are then ejected 

 into the cell-sap 3 . This probably often occurs, the poison combining with 

 some substance already present in the cell. If no renewed formation 

 of this substance is induced then only a limited quantity of poison 

 can be disposed of. There can, however, be little doubt that in particular 

 cases reactions may be excited which tend to the removal or destruction 

 of the poison. The protoplasm is able to restore its original alkalinity 

 after it has been made feebly acid. If this were continuous then the 

 poisonous action of slowly penetrating dilute acid might be neutralized, 



1 Cf. Loew, System d. Giftwirkungen, 1893. 



2 Pfeffer, Unters. a. d. Bot. Inst. zu Tubingen, 1886, Bd. II, pp. 248, 259, 274. 



3 Id., 1. c., p. 262. 



