380 HEMOLYSINS 



test-tube, cooling to C. for half an hour, heating subsequently to 

 37 C. for three hours. The presence or absence of hemolysis is observed, 

 and the results compared with those obtained from normal blood 

 treated in the same manner and at the same time. 



Third Method. This technic is carried out in vitro in the following 

 manner: Pipet 2 c.c. of the patient's blood in a small test-tube and 

 separate the serum. At the same time place 1 c.c. of blood in a centri- 

 fuge tube containing 9 c.c. of a 1 per cent, solution of sodium citrate in 

 normal salt solution. Wash the corpuscles twice and suspend the sedi- 

 ment in 10 c.c. of normal salt solution. Then, secure a cubic centimeter 

 of a fresh serum from a normal person. Proceed to make the following 

 mixtures : 



Tube 1 : 0.2 c.c. patient's serum -J- 1 c.c. corpuscle suspension. 



Tube 2: 0.1 c.c. patient's serum -f- 1 c.c. corpuscle suspension. 



Tube 3: 0.2 c.c. normal serum + 1 c.c. corpuscle suspension. 



Tube 4: 0.1 c.c. normal serum + 1 c.c. corpuscle suspension. 



Tube 5: 1.0 c.c. corpuscle suspension. 



Add sufficient normal salt solution to each tube to make the total 

 volume measure 2 c.c. Shake gently, and place in the refrigerator at a 

 low temperature (not higher than 4 C.) for an hour. Shake each tube 

 gently and place them in the incubator at 37 C. for two hours. The 

 tubes are then centrifuged and the presence or absence of hemolysis 

 is noted. Usually the patient's serum shows hemolysis of greater or 

 less degree. 



Similar mixtures may be made with the patient's serum and the cor- 

 puscles of a normal person. The hemolytic substance is capable of lysing 

 these to the same degree that it does the patient's own cells. 



METHOD OF DETERMINING THE RESISTANCE OF RED BLOOD-CORPUSCLES. 

 NON-SPECIFIC HEMOLYSIS 



Various substances have been employed to test the resistance of the 

 red blood-corpuscles. Of these, the hypotonic solutions of sodium 

 chlorid, of varying strength, have yielded results of clinical importance, 

 especially in the study of paroxysmal hemoglobinuria, the primary ane- 

 mias, etc. 



The following technic, slightly modified after the methods used by 

 Smith and Brown, Gay, Moss, Karsner, and Pearce, is a ready means 

 for determining the resistance of human corpuscles to salt solutions of 

 different tonicities. Chemically pure sodium chlorid is dried for two 

 hours at 170 C., and immediately weighed in amounts necessary to 



