19?^ 



pOAverful poisonous actio]i 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: — " WJiile various explaiiatious might be offered to 

 show Avliy sucli exlremely uiinute quantities of copper in 

 solution are suhicient to kill unicellular and filamentous 

 algae, bacteria and unicellular animal organisms, and yet 

 not att'ect multicellular plants and animals, whose cells 

 are as delicate in structure as those of the unicellular 

 organisms, it seems that tliis 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 i)rocesses 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-sealed 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 Locke' that the 

 })oisonous action of minut(> traces of copj)er is not confined 

 to unicellular organisms. Merely placiiig strips of quite 

 clean metallic copper in water in Avhich tadpoles are kept 



* Proc. Amer. Philosoph. boc. vol. xlix., Ko. 179,. p. 51, April, 

 1906, where full references to the literature of the subject -svill be 

 found. 



I Jouni. of Physiology, 1895, vol. 18, p. 319. 



