VENOM HEMOLYSIS IN SYPHILIS 409 



of serum will be removed. After completing the last centrifugaliza- 

 tion, which should be thorough (ten minutes), the cells are diluted with 

 25 volumes of normal saline solution, which makes a 4 per cent, sus- 

 pension for instance, 0.8 c.c. of corpuscles would require 20 c.c. of 

 diluent. 



Just what influence sodium citrate has upon the process is not 

 known, but it is certain that satisfactory results are seldom obtained 

 with blood defibrinated by whipping with rods of glass beads. Similarly, 

 if centrifuged too rapidly, cells are broken up or rendered more sus- 

 ceptible to the venom ambocepter. 



The Test. Into a series of five test-tubes (4 by % inches) place 

 1 c.c. of each dilution of venom, and label each tube correctly; add 1 c.c. 

 of the 4 per cent, suspension of cells to each tube, shake gently, and incu- 

 bate for one hour at 37 C. Except in cases where the venom dilutions 

 are being frequently used and are known to be reliable, controls should 

 be included. I usually add a normal control of cells from a healthy 

 person with the 1 : 30,000 or 1 : 40,000 dilution and expect complete 

 hemolysis to occur. A preliminary reading is made at the end of an 

 hour; the tubes are shaken gently and placed in the refrigerator over- 

 night; the final reading is made next morning, and should tally quite 

 closely with the preliminary reading. 



Reading the Results. Unless the cells are derived from a very strongly 

 reacting case of syphilis, the 1 : 10,000 dilution will be hemolyzed. The 

 normal control tube should show complete hemolysis. If the 1 : 10,000 

 tube is not hemolyzed and some of the higher dilutions show hemolysis, 

 an error in technic has occurred, and the test should be repeated with 

 fresh dilutions. 



The reactions are read and recorded as follows (Fig. 107) : 



ABODE 



H. M. H. = strongly positive. 



H. H. M. H. = moderately positive. 



H. H. H. S. H. = weakly positive. 



H. H. H. H. M. H. = negative. 



H. H. H. H. H. = certainly negative. 



H. = complete hemolysis; M. H. = marked hemolysis; S. H. = slight hemolysis; 

 the dash ( ) = no hemolysis. 



If complete hemolysis has occurred in all tubes after an hour's 

 incubation, the cells are regarded as being hypersensitive to cobra 

 venom. This occurs as a rule in primary syphilis and in active tuber- 

 culosis. 



