181] 



THE GOLDFISH AS A TEST ANIMAL— POWERS 



61 



CdCU, and FeCls. See page 35. Kfizeneck^ (1916) in his work on Enchy- 

 traeus humicuUor, a fresh water annelid, showed that the survival time of 

 these worms in different concentrations of sea-water, when data is plotted as 

 above, gives a similar curve. Knzeneck;^ explained these results as well as 

 the greater part of the toxic effect of the alkali and alkaline earth metals 

 tested by him as being due to osmotic pressure. He then formulates a curve 

 by tabulating results obtained by determining the time required for the worm 

 to recover in ordinary tap-water after being placed in different concentrations 

 of sea-water for one minute. He then states that both curves have the charac- 

 teristics of curves of autocatalytic processes in that they fall within the province 

 of the theory of the temporal properties of Ufe processes proposed by Ostwald 

 (1908). Loeb (1903) in summarizing his work on a marine Gammarus, states 

 that, "if sea-water be diluted by the addition of distilled water the duration 

 of life decreases at first only slightly in the decrease of the degree of dilution. 

 But as soon as a dilution of ten times is reached an abrupt decrease in the dura- 

 tion of life takes place with further dilution. Whether the curve of the dura- 

 tion of life at this place is discontinued is not yet proven. " Data obtained 

 from the work of Loeb and Wasteneys (1913) on the reduction of oxidation 

 of fertilized eggs of sea-urchins by the addition of .01% KCN solution to sea- 

 water gives a similar curve when per cent of loss of rate of oxidation is plotted 

 as ordinate and relative amount of KCN added to the sea-water as abscissa, 

 Fig. 27. The per cent of reduction of the rate of oxidation of an individual 

 sponge as given by Hyman (1916) in her work showing the effect of KCN on 

 the reduction of the rate of consumption of oxygen by a marine sponge also 

 gives a similar curve when per cent of reduction of oxygen consumption is 

 plotted as ordinate and normaUty of KCN as abscissa (only data on a single 



Per Cent. 

 100 



80 



60 



40 



20 





Figure 27. Curve showing the effect of potassium cyanide on the rate of oxygen absorp- 

 tion of fertihzed eggs of the sea urchin. Abscissa represents cc. of 0.01% KCN p>er 50 cc. 

 sea-water. Ordinate represents the per cent of reduction of rate of ox>'gen absorption below 

 the normal by the potassium cyanide. 



