1893. EXPERIMENTS ON LIVING CELLS. 433 



laboratory in a brass tap. The first litres drawn were strongly oligo- 

 dynamic, from contact with the lead and with the copper of the tap ; 

 after some quantity had been run off, the water was neutral. The 

 distilled water was rendered hurtful by the apparatus used. Neutral 

 water could be obtained at any time by distilling in glass alone. 



Nageli's papers on oligodynamics were handed to Professor 

 Cramer of Zurich in the spring of 1892, who at once instituted a care- 

 ful examination of the recorded experiments, with the result that this 

 peculiar power of weak metallic solutions was completely verified. 

 He followed very much on the lines of the previous research, testing 

 the effect on Spirogyva cells of copper, copper sulphate, mercury, 

 mercuric chloride, and Dr. Low's solution of alkaline silver nitrate, 

 and the results, with slight variations, corresponded to those already 

 determined by Nageli. 



The water used in Ziirich comes from the lake, is exceptionally 

 pure, and is conveyed to the town in iron pipes. With the exception 

 of the first litre drawn, which had been in contact with the brass tap 

 of the laboratory, it was, in Nageli's sense, absolutely neutral. The 

 distilled water usually employed was prepared in a copper vessel 

 lined with tin. It reacted variously, and especially seemed to lose 

 oligodynamic power if it had been in several vessels, or if it had 

 stood some time after preparation. In this connection, we may also 

 note that he found the oligodynamic reaction was in proportion to the 

 size of the vessel used in experiments. If there was much of the 

 metallic solution in a small vessel, the effect on the cells was rapid ; ^ 

 the same solution acted much more slowly when a drop of it was 

 used on a glass slide where the glass surface exposed was so much 

 greater in proportion to the quantity of metallic molecules present. 

 The solution became weaker the longer it was allowed to stand, and 

 repeated boiling or filtering neutralised it altogether. Water dis- 

 tilled in glass was, he also found, invariably neutral. 



Professor Cramer chose, for the purpose of research, three species 

 of Spivogyra ; one of these, Sp. quinina, is of a delicate texture with 

 only one spiral chlorophyll band, the other two, Sp. densa and Sp. 

 setiformis, are coarser. The reaction depended, to a certain extent, 

 on the species ; Sp. setiformis, with closely-wound spirals, always 

 resisted the action of the metal longer than the other two species. 

 The sensitiveness of the plant was, however, intensified if it had 

 been long under cultivation in the warm temperature of the labora- 

 tory, in which case the cells lengthened, and the spirals were, in 

 consequence, looser and more sparse. He used for his control 

 cultures large glass vessels filled with ordinary Ziirich water. 



Oligodynamic reaction was most easily obtained by water in 

 which copper had remained from one to three days. If a healthy 

 plant growing in neutral water were strewn with copper turnin'gs, 

 the chlorophyll bands very quickly shrunk from the sides of the cells 

 in contact with the copper, A glass slide that had been in contact 



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