i9°S-J 



ON INTESTINAL ORGANISMS. 51 



THE OLIGODYNAMIC ACTION OF COPPER FOIL ON 

 CERTAIN INTESTINAL ORGANISMS. 



BY HENRY KRAEMER. 



( Read April /j, 1903. ) 



Carl von Nageli, probably the greatest botanist of the last cen- 

 tury, being both a philosopher and a true scientist, passed away on 

 May 10, 1 89 1. Among his papers was found the manuscript of a 

 paper entitled " Ueber oligodynamische Erscheinungen in lebenden 

 Zellen," which, together with an added note by Cramer, was pub- 

 lished by Schwendener several years after his death in Neue Denk- 

 schriften der schweizerischen naturforschenden Gesellschaft. 1 



This really remarkable paper, while it has attracted considerable 

 attention, does not seem to have been given the credit in some 

 quarters that its merits deserve. In the light of more recent bio- 

 logical studies it has proved to be one of the most important papers 

 that was written by Nageli, and illustrates both the fertility of his 

 resources and the incisiveness of his genius. 



In this paper Nageli showed how exceedingly sensitive certain 

 living plants are to very minute quantities of various metals. For 

 forty years he had been studying the algae, but it was not until some 

 time in the '8o's during an illness that he observed that if alga? 

 were placed in distilled water they were killed. This he at first 

 attributed to various causes, but found upon analysis of the water 

 that it contained traces of copper, and later experiments showed 

 that the copper, which had been dissolved by the water in its pas- 

 sage through the copper still, was the toxic agent. He then carried" 

 on a large number of experiments placing copper coins in distilled 

 water, and even went so far as to calculate approximately the amount 

 of copper which was dissolved. 



1 For example, in the English translation of Pfeffer' s Physiology of Plants, Vol. 

 II, page 260, it is stated that copper is poisonous to Spirogyra in the proportion 

 of one part of copper to 1,000 million parts of water, an observation made by 

 Nageli in the paper referred to above, and yet no mention of this paper is made in 

 the citation of literature, which would lead the reader to believe that one of the 

 other investigators quoted deserved the credit for the discovery. 



