METHODS FOR OBTAINING IMMUNE SERA. 125 



tion than do agglutination or bacteriolytic tests. With the majority 

 of other organisms, however, the agglutination test is the one almost 

 always preferred. 



Even in a small laboratory there are no particular difficulties in the 

 way of having on hand rabbits immunized against typhoid, paratyphoid 

 Malta fever, acid producing and nonacid producing strains of dysentery, 

 cholera, etc. Just as we inject men with vaccines prepared from 

 various bacteria in opsonic therapy, so we inject animals to produce sera 

 for diagnosis. We may use either a bouillon culture or the growth on 

 agar. slants taken up with salt solution as the inoculating material. 

 This is heated for one hour at 60 C. to kill the bacteria. Where we 

 desire to produce a serum which will disintegrate red blood cells 

 (haemolytic serum), we inject about 4 c.c. of the defibrinated blood of 

 the animal for which we wish to produce a specific serum. Thus for 

 a serum for use in a medicolegal case we would inject the rabbit with 

 human blood. The most convenient way to defibrinate blood is to 

 break a section of glass tubing into fragments, put these fragments 

 into a glass test-tube, sterilize tube and contents in a flame or sterilizer 

 and, when cool, let the blood drop into the test-tube (we may use a 

 Wright's pipette with a rubber bulb to take up the blood from a punc- 

 ture of the finger and eject it into the tube). By shaking, the fibrin 

 collects on the glass fragments, and we have the corpuscular emulsion 

 to inject. Inject about 4 c.c. of the defibrinated blood or i c.c. of the 

 killed bacterial bouillon culture into the peritoneal cavity of the rabbit. 

 The easiest w r ay to inject the rabbit is to hold the animal head down 

 and plunge the needle in the median line into the abdominal cavity, 

 forcing in the contents of the syringe. The intestines gravitate down- 

 ward and by entering the needle below the limits of the bladder 

 we avoid injuring any vital part. It may be more satisfactory to at 

 first inject only about 1/2 c.c., and then if there is very little reaction, 

 as shown by the appetite and spirits of the rabbit, to inject about 4 

 days later i c.c. About 4 or 5 injections at intervals of 3 to 5 days 

 will usually produce an immune serum. Some animals do not seem 

 to be capable of producing antibodies, so that it may be necessary to 

 use one or more rabbits before a satisfactory serum is obtained. The 

 most convenient way of obtaining serum for a test is to cut across one 



