342 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



powerful poisonous action on certain living forms and to 

 be harmless to others, and the subject deserves further 

 investigation. It is possible that it may prove to act 

 prejudicially to some human parasites, and it is certainly 

 less dangerous to man than many other remedies used as 

 parasiticides and disinfectants." 



Kraemer, in a recent paper,* commenting on this 

 says: — " While various explanations might be offered to 

 show why such extremely minute quantities of copper in 

 solution are sufficient to kill unicellular and filamentous 

 algae, bacteria and unicellular animal organisms, and yet 

 not affect multicellular plants and animals, whose cells 

 are as delicate in structure as those of the unicellular 

 organisms, it seems that this is in a measure due to the 

 fact that in the latter the entire individual is comprised 

 of a single cell, which performs all the vegetative as well 

 as reproductive functions, and being entirely surrounded 

 by the copper solution all the life processes are affected, 

 there being no way for the organism to distribute the 

 solution to other cells, and thus by a dilution minimise 

 the toxic action of the copper. Or if some of the cells in 

 the multicellular organism are destroyed or injured by 

 exposure to the solution, others are formed to take their 

 place from the more or less deep-seated meristematic cells. 

 It is true that the idiosyncrasies in these organisms should 

 also be borne in mind, some of them being more resistent 

 than others." 



It has been shown, however, by Locket that the 

 poisonous action of minute traces of copper is not confined 

 to unicellular organisms. Merely placing strips of quite 

 clean metallic copper in water in which tadpoles are kept 



* Proc. Amer. Philosoph. Soc. vol. xlix., No. 179, p. 51, April, 

 1905, where full references to the literature of the subject will be 

 found. 



f Journ. of Physiology, 1895, vol. 18, p. 319. 



