THE WASSERMANN TEST 79 



for some time tried to find a chance to apply his test to dourine of 

 horses, but, unfortunately, no occasion has offered. Very probably 

 the test could be made in an identical manner, but this would, of 

 course, have to be tried out first experimentally. The serum test 

 for the diagnosis of syphilis was devised by Wassermahn and his 

 co-workers, Neisser and Bruck. It is generally known simply as the 

 Wassermann test. 



The following reagents and preliminary steps in their proper 

 arrangement, dilution, etc., are necessary: 



1. The red blood corpuscles of the sheep are used for the final 

 hemolytic tests. They must be washed free from all blood serum. 

 The blood is obtained either from the jugular vein of the live animal 

 or from a slaughter house at the time when the animal is killed. It 

 is best to have the blood run into a sterile vessel, though this is by no 

 means absolutely necessary. It is at once defibrinated by beating it 

 with a bundle of wires or glass rods or by shaking it with some frag- 

 ments of glass or glass pearls. After the fibrin has coagulated there 

 remains an intensely red fluid containing the serum and the cor- 

 puscles. Some of this fluid is mixed in the proportion of one to ten 

 with physiologic salt solution. Two centrifuge tubes are filled with 

 the mixture, and these are centrifuged for from five to ten minutes. 

 There is now formed a deposit of corpuscles and an upper layer of 

 clear fluid. The latter is pipetted off; the tubes are again filled with 

 normal salt solution, shaken so that the corpuscles and the fluid are 

 mixed; they are centrifuged again and the clear fluid is pipetted 

 off once more. This is done at least three times. Finally, about one 

 part of the washed sheep's corpuscles is mixed with nineteen parts 

 of physiologic salt solution and shaken until an emulsion is obtained. 

 The latter is called the 5 per cent, emulsion of washed sheep's cor- 

 puscles. 



2. In order to make the test properly it is necessary to have a 

 strong hemolytic amboceptor. This is obtained by "sensitizing a 

 rabbit against sheep's corpuscles" in the following manner: The 

 abdominal region of the rabbit is shaved and cleansed antiseptically. 

 The animal is then held up by two assistants in such manner that 

 its head hangs down and the hind legs, which are spread out, point 

 upward. In this position the rabbit's intestines fall toward the 

 diaphragm and there is little danger of injuring them in the next 

 step, which consists in injecting into its peritoneal cavity about 10 c.c. 

 of a 5 per cent, physiologic salt emulsion of washed sheep's cor- 

 puscles (this must have been freshly prepared under aseptic precau- 

 tions and the injection must be made with a sterile syringe). This 

 procedure is repeated three or four times or oftener at intervals of 

 about ten days. The blood serum of a rabbit so treated will have, 

 as a rule, a very strong hemolytic power toward sheep's corpuscles. 

 Since the serum is sometimes deficient in spite of the injection treat- 

 ment, it is well to draw some blood from an ear vein and test it 



