26 



Sixteen-eiibic oentiiaeter suspension : Transplants same as 8- 

 cubic centimeter suspension. 



Tliirty-t\vo-cu))ic centimeter suspension: Transplants developed 

 few amoeba^ and few sjiirilla. 



The 16-cubic centimeter control suspensions with copper omitted, 

 gave practically the same results as did those containing the copper, 

 except that the cholera spirillum grew rather feebly in those treated 

 with copper but freely in those untreated. 



In the 38-cubic centimeter suspensions without copper the 

 growth of ania>ba3 and spirilla was distinctly better than in those 

 treated with coj^per. The transplants from the suspensions treated 

 with copper to cholera plates developed a rich growth of amoeba?. 



We may fairly make the following deductions from the foregoing 

 experiments: First, that high dilutions of cupric sulphate have 

 practically no effect within ninety-six hours, upon concentrated 

 suspensions of amoeba^. (8-cnbic centimeter solution to one 

 forty-eight-hour slant agar culture) ; second, that copper solutions 

 as dilute as 1—100,000 have little, if any, specific effect on the 

 amoebse, though they inhibit the growth of the cholera spirillum 

 to an appreciable extent after an exposure of ninety-six hours, in 

 dilutions as high as 32 cubic centimeters of copper solution to one 

 forty-eight-hour slant culture, and thus impede somewhat the 

 development of the amoeba?. However, it is very doubtful whether 

 this inhil)iting action on the spirilla is of sufficient potency, even 

 in dilutions of 1-100,000, to exercise any practical effect on the 

 development of amoebse in large bodies of water. 



After presenting several tables of experimental data as to the 

 action of "colloidal solutions of copper" on the colon bacillus, the 

 cholera spirillum, and other bacteria, Moore makes the following 

 statement in Bulletin No. 6Ji- mentioned above : 



It is evident that the amount of surface exposed in any ordinary copper 

 tank would far exceed the amount demanded for the above results, and it 

 is likewise certain that after standing from six to eight hours at room 

 temperature in a clean copper vessel water becomes safe to drink even 

 though it may have contained cholera and typhoid germs. It remains to 

 be seen whether or not the application of these facts to conditions in the 

 Tropics, where cholera is abundant, will be of any value. It would seem 

 that the construction of canteens and other water vessels from copper might 

 serve as an additional safeguard, if not an actual preventive of this 

 disease, and would prove of considerable value where distillation or efficient 

 filtration apparatus is not at hand. 



