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A Method for Investigating the Hcemolytic Activity of Chemical 



Substances. 

 By Eric Ponder. 



(Communicated by Sir E. Sharpey Schafer, F.R.S. Received May 13, 1921.) 

 (From the Department of Physiology, University of Edinburgh.) 



Introduction. 



Arrhenius has pointed out that the phenomenon of hsemolysis may be 

 ■described by the qt. rule.* In this investigation it has been found that 

 this rule is quite insufficient to describe the relation between the quantity of 

 a haemolytic agent and the time which such quantity takes to produce 

 haemolysis, unless a large margin of error be admitted. Since in some of the 

 •examples quoted by Arrhenius, the end point was not complete hajmolysis, 

 but a certain percentage, it is easy to see that the difficulties of investigation 

 account for the fact that the discrepancy between results given by experiment 

 and those obtained by the use of the qt. rule has been overlooked. Further 

 it is recognised that this rule is not of general application ; being inapplicable, 

 for instance, in the case of sodium oleate. In order to remove the difficulty 

 of investigation, a technique of great accuracy has been introduced ; the 

 results of experiments will be found to require a description other than that 

 furnished by the qt. rule. 



Special Apparatus Required. 



(1) A set of pipettes to deliver 1, 2, 3, 4 and 5 c.c. 



(2) Pipettes, 1 c.c. capacity, graduated in 0"01 of a cubic centimetre. 



, (3) Burettes and pipettes of convenient capacity, and tared flasks of 50 and 

 100 c.c. capacity. 



All volumetric apparatus must be certified, or preferably calibrated by the 

 •experimenter. 



(4) Tubes, about 1x3 inches, with flat bottoms for preference ; these have 

 rubber stoppers, with one perforation for the passage of a thermometer, 



(5) About twelve thermometers, graduated from 0° C. to 50° C. and capable 

 of being read to 1/10 of a degree: these must all be checked against a 

 standard instrument. The bulbs should be small, and the scale arranged so 

 that it shall be above the level of the stopper of the tube when the thermo- 

 meter is in position. 



* Arrhenius, S., ' Quantitative Laws in Biological Chemistry,' 1915, p. 63, seq. 



