HEMOLYTIC STAPHYLOCOCCI 9 



determine whether a hemolytic strain of staphylococcus is always 

 hemolytic. No definite references to the loss of this haemolytic 

 manifestation could be found in the literature. Transplants were 

 made daily into peptone broth, and at the end of each week blood- 

 agar plates were streaked to show whether the cultures were still 

 hemolytic. After the second week, since the plates were readily 

 hemolyzed, the cultures were transplanted every other day, and after 

 the first month every week. The reason for this change of procedure 

 was the assumption that by daily transplantations the cultures were kept 

 very active and that it would be more difficult, if possible, to suppress so 

 vital a quality. 



This experiment was continued for more than four months, and at 

 the time of writing the cultures were still hemolytic. On some occasions 

 there appeared to be retardation in hemolysins, and then the following 

 week the cultures were as actively hemolytic as originally. -Since the 

 retardation was neither progressive nor continuous, it is reasonable to 

 assume that it was probably due to differences in the blood used for the 

 work. Normal horse blood, which was used for the blood-agar plates 

 in this experiment, has been shown by Neisser and Wechsberg 2 to 

 possess small quantities of antihemolysin. This normal quantity, how- 

 ever, may have been sufficient to delay nemolysis. It would seem, 

 therefore, that hemolytic cultures tend to remain hemolytic. 



Effect on Nonhemolytic Strains of Successive Transplantations in 

 Blood Medium. In this case the point at hand was to determine 

 whether nonhemolytic cultures could be made hemolytic by adaptation 

 to blood medium. If nonhemolytic cultures can be made to lake blood, 

 it may be said that any strain of staphylococcus is hemolytic, adding 

 provisionally that continual adaptation to a blood-free habitat ultimately 

 suppresses its hemolytic activity and keeps it in abeyance ; but readapta- 

 tion to a blood-containing medium will restore the suppressed activity. 

 Table 3 shows that after a period of 7 months, certain strains regained 

 their hemolytic ability. It may be that this power was recovered at an 

 earlier period, but tests were not definitely made until the stated lapse 

 of time. 



It should be added here, in view of a wealth of work in a hospital 

 laboratory, that we think every strain of staphylococcus is definitely 

 hemolytic. The strains will vary in degree of hemolysis, and in rapidity 

 of hemolysis, but if sufficient time is given, all strains will show hemol- 

 , ysis. When the strains under study were isolated, a period of 6 days 

 was given to determine hemolysis on blood plates, and it is now apparent 



