JUNE, 1893. EXPERIMENTS ON LIVING CELLS. 429 
nucleus into a round ball. To this latter result Nageli gave at first 
the name Jsayitdt, but later he changed it to Oligodynamic. 
As to the effect of solutions generally on Spivogyva and other cells, 
Nageli enumerates three ways in which they may prove fatal—physi- 
cally, by inducing plasmolysis, for instance; chemically, by poisoning 
the plant; and lastly, oligodynamically. The last-mentioned resulted 
when the chemical solution was so diluted that the reaction could not 
be one of simple poisoning, but must be due to some other influence. 
Nageli pursued the research still on the same lines; he put the 
filaments into Dr. Léw’s solution, diluted quadrillion-fold, till, finally, 
he concluded that no calculable trace of the poisonous silver nitrate 
was present; the result was equally satisfactory from an oligodynamic 
point of view, the cells died often in less than four minutes. He now 
turned his attention to the water used in the solution, which was 
distilled in the ordinary way, and the conclusion arrived at wasa 
startling one, namely, that pure water is a dangerous and hurtful 
fluid. After boiling, the evil effects diminished, they did not quite 
disappear. 
Another series of experiments was tried with mercuric chloride— 
a still stronger poison. This was diluted down to septillion-fold, and 
the plants died as before. Professor Cramer has calculated that in 
order to dilute 1 milligramme of mercuric chloride to this extent, we 
should require more water than there is on our planet. A globe of 
water would benecessary thirteen million geographical milesin diameter, 
which would reach almost from the sun to Venus, and the molecules 
in such a solution would be separated from each other by a distance 
equal to two-thirds of the earth’s diameter. He concluded, as we 
do, that the solution would be harmless, so far as mercuric chloride 
was concerned. This experiment proved conclusively that the evil 
was due to something other than chemical poison. 
Attention was next turned to the glass vessels used, to see if the 
effect was produced by mechanical action. The glasses were tested 
in various ways, by movement, by covering them, etc., but no diffe- 
rence was visible in the behaviour of the solution ; the Spirogyra died, 
and yet not always; in four out of this series of experiments the 
Spivogyva remained uninjured in the diluted solution. Again, boiling 
was tried, and in most cases the water was restored—we can hardly 
say to purity, but to harmlessness, or, as Nageli terms it, it was 
rendered reutral. 
Meanwhile, control experiments with pure distilled water had 
been carried on quite successfully in glasses full of Spirogyra. A 
culture was now tried with the same water and only a few filaments ; 
as Nageli expected, they died, if anything, still more quickly than in 
the diluted chemical solution, and water from the tap acted frequently 
exactly like distilled water. 
A further research was now entered on to test the water, and as 
distilled water was, on the whole, more fatal than tap-water, he 
