54 KRAEMER— ACTION OF COPPER FOIL [April i 3> 



While Niigeli's paper was incomplete he nevertheless had carried 

 on a sufficient number of experiments to show that there is a 

 marked difference in the sensitiveness of various species of 

 Spirogyra to the oligodynamic action of copper. He found, for 

 instance, that Spirogyra orthospera and other Spirogyra s with lense- 

 shaped nuclei were more resistant than the remaining species. 1 

 He also showed that there was a marked difference in the sensitive- 

 ness in some of these plants (S. m'tida) at different times of the 

 day. 



While Niigeli confined his attention to studies on Spirogyra 

 using copper coins 2 to produce the oligodynamic effects, other in- 

 vestigators since his time have carried on experiments with other 

 organisms both plant and animal and have employed metallic cop- 

 per and salts of copper as well. One of the most important of 

 these researches is that by Israel and Klingmann. 4 These investi- 

 gators studied the effects of copper on certain bacteria (as Bacil- 

 lus typhi, B. coli and Microspira comma'), as well as certain animal 

 organisms (as Amoeba, Difflugia oblonga, Hematococcus pluvialis, 

 Paramecium Bursaria, Spirostomum ambiguum, Vorticella micro- 

 stoma and Sty lony chia mytilus), and also on Spirogvra. They used 

 copper foil and found that it had a marked toxic effect on all of 

 the bacteria that they worked with, B. typhi being the most 

 sensitive. They also found that by placing the solutions of 

 copper containing the organisms in an incubator at a temperature 

 of 35°-4o° C. the toxic effects were manifested in i hour, whereas 

 at the ordinary temperature similar effects were produced in two 

 hours. In the case of the animal organisms, while the toxic effects 

 were visible in most instances in but a few minutes, in Vorticella it 

 required several hours for any toxic effects to be observed and it 

 was found that Sty lony chia might resist the action for 24 hours. 

 These authors further found that water in which copper foil had 

 been placed for 24 hours, could be diluted 100 times and still 

 manifest oligodynamic effects on Spirogyra. In the latter instance 



1 Cramer made a similar observation with S. setiformis (?). 



Israel and Klingmann (page 307) found that S. Crassa was killed in 15 min- 

 utes, S. majuscula in 30 minutes and S. laxa in 75 minutes. 



2 During his investigation Nageli also discovered that minute quantities of other 

 metals, as silver, lead, tin, iron and mercury manifested oligodynamic properties 

 similar to copper. 



