74 MECHANISM OF DISINFECTION AND HEMOLYSIS 



content and the dry weight of the residual cells at various stages of 

 hemolysis. 



Since none of the explanations given above is satisfactory let us 

 see whether the experimental facts necessitate the assumption that 

 the equation of the monomolecular reaction is a complete description 

 of the process of disinfection. Examination shows that none of the 

 experiments already referred to include the observations necessary 

 for the study of the first part of the process; the second observation 

 was almost without exception deferred until the process was nearly 

 half complete. It also appears that in many experiments the "initial" 

 number of cells was determined after an appreciable part of the process 

 had occurred, that is after the most fragile cells had already suc- 

 cumbed, and while the reaction was proceeding so rapidly that the 

 slightest errors in the time of sampling would produce great differences 

 in the number of cells recorded. 



It is quite impossible to judge correctly the vahdity of formulas 

 based on such inadequate data. In Fig. 5, 1 have plotted the points 

 of that one of Chick's curves which shows the best agreement with a 

 monomolecular reaction curve, a similar curve for the number of 

 CJilamydomonas cells immobihzed at intervals after exposure to 

 dilute hydrochloric acid (Harvey ,^^), a curve for normal serum hemol- 

 ysis (Henri, ^1), and an original curve (from which the first few ob- 

 servations are omitted) for hemolysis after ultra-violet radiation. In 

 the last two cases hemolysis was estimated colorimetrically. A 

 monomolecular reaction curve is drawn for comparison with these 

 points, and the scales of the abscissae are so arranged as to make the 

 curves coincide at the point where the effect is half cornpleted. The 

 agreement of the points with the monomolecular reaction curve is 

 about equally close. But in this same figure the curve for the original 

 hemolytic experiment is also drawn with the abscissae on a larger 

 scale and with the first few observations included. It is obvious that 

 these first few observations are most important. One suspects 

 that had these observers but made sufficient observations during the 

 first part of the process, they would have found that disinfection, 

 kilhng of seeds, etc., are processes which, like hemolysis, are initially 

 slow and only subsequently attain their maximum velocity. As a 

 matter of fact this is what a number of other workers have found. 



