III. 

 Naegeli's Experiments on Living Cells. 



A SHORT notice of Carl von Nageli's paper, " Uber oligodynamische 

 Erscheinungen in lebenden zellen," concerning the fatal effect 

 of " nominally " pure water on living cells, appeared in Natural 

 Science (May, p. 333). The following is an account of the experi- 

 ments by which Nageli arrived at his conclusions. The record of 

 this work, which was carried on in his laboratory at Munich, was 

 found by Schwendener among his papers after his death. Professor 

 Cramer, of Zurich, went carefully over the ground a second time and 

 obtained the same results as his old master. 



The research, we are told by Schwendener, dates from the year 

 1880. Dr. O. Low and Dr. Bokorny had recently published a paper 

 on the reduction of silver salts by living protoplasm. While verifying 

 for himself the results arrived at b}' these gentlemen, Nageli was led 

 to turn his attention from the effect of living cells upon silver salts to 

 the reverse action of the silver salts on living cells. 



The Spirogyra experimented on is a very common fresh-water 

 Alga ; it is composed of long cylindrical filaments, divided up at 

 regular short intervals into cells, with spiral parietal bands of chloro- 

 phyll. The spirals may be single or double, and they, as well as the 

 cells, vary in size in the different species. These differences affected, 

 to a considerable extent, the sensitiveness of the plant under examina- 

 tion ; the more compact the spirals the greater the resisting power of 

 the cells. It was also found that resistance to any hurtful influence 

 was at its maximum towards the close of the day, when there was a 

 great accumulation of assimilation products in the chlorophyll bands. 

 In the early morning, when these were withdrawn and dispersed 

 through the cells, the plant was much more sensitive. 



The alkaline solution of the silver salt used by Nageli in his 

 experiment was the one prepared by Dr. Low (containing i Ag NO,, 

 I NH.,, 3*6 K.jO to 100,000 volumes of water), which killed the plant 

 by poisoning it ; the cells lost their turgidity, the protoplasmic layer 

 shrunk away from the walls, the chlorophyll bands changed colour 

 and gradually became disintegrated. With further dilution the cells 

 still died, but in a totally different manner ; the turgidity of the cells 

 and tlie protoplasmic layer remained unaffected, the chlorophyll 

 bands alone seemed to be sensitive, they shrunk together with the 



