THE WASSERMANN TEST 177 



100 dilution. To i c.c. of a J^% emulsion of red cells we add o.i c.c. of a 40% dilu- 

 tion of guinea-pig's fresh serum similar combinations being made in a series of 

 10 tubes. To each of these tubes we add varying amounts of the i to 100 dilution, 

 o.i c.c. in the first, 0.2 c.c. in the second, 0.3 c.c. in the third, and so on. If we 

 obtain haemolysis in the tube containing 0.2 c.c. of i to 100 dilution of serum but not 

 in that containing o.i c.c. we note that the serum has a titer of about i to 500. If 

 the o.i c.c. gave haemolysis, the serum would have a titer of i to 1000. 



Having ascertained that the haemolytic serum is sufficiently strong we shave the 

 left side of the thorax of the rabbit and enter the needle of the apparatus similar to 

 that used for taking the blood from a man's vein in one of the intercostal spaces of the 

 left side. 



Having introduced the needle, feel for the heart beat and then plunge the needle 

 into the heart. We can withdraw about 30 c.c. of blood without injury to the rabbit. 

 This blood should be received in a clean empty flask and set, over night, in the re- 

 frigerator. The following morning pour off the clear serum into a clean Petri dish 

 and saturate, one by one, squares of filter paper with the serum. Allow the filter 

 paper to dry on a piece of unbleached muslin. Noguchi recommends Schleich and 

 Schull's paper No. 597. When thoroughly dry cut strips 5 mm. wide. This makes 

 the amboceptor paper. To standardize, take a series of tubes containing i c.c. of 

 a K% emulsion of red cells and add o.i c.c. of 40% dilution of guinea-pig serum for 

 complement. Next cut across the amboceptor paper strip pieces of varying width, 

 as i mm., 2 mm., 3 mm., 5 mm., and so on. The narrowest strip which gives haemo- 

 lysis in one hour in the incubator or one-half hour in the water-bath equals i unit. 

 Thus if a piece 5 mm. wide was required to produce haemolysis, 5 mm. of the paper 

 would have a value of i unit. 



Coca injects rabbits intravenously with i c.c. of well-washed red cells 

 and five days later gives a similar dose intravenously. The blood for 

 the haemolytic serum is taken from the rabbit five days after the second 

 and last injection. He states that such a method not only gives a 

 high titer but avoids to a great extent agglutination difficulties. It 

 also is more stable as regards holding its original titer. We have had 

 better success with the following method than with Coca's. Inject in- 

 travenously Y c.c. of 50% red-cell suspension and three days later 

 inject ^ c.c. of the same strength suspension. Several days later in- 

 ject i c.c. and withdraw seven days afterward. 



THE WASSERMANN TEST 



In the Wassermann reaction the rabbits are injected with sheep 

 red cells which have been washed twice with salt solution by aid of the 

 centrifuge. About five intraperitoneal injections with, on the average, 

 the quantity of red cells contained in 5 c.c. of sheep blood, given at in- 

 tervals of five days, gives a strong haemolytic serum if taken about 

 one week after the last injection. 



12 



