30 QUATERCENTENARY STUDIES IN PATHOLOGY 



The Protective Action of Anti- Plague Serum. — Though much 

 sceptical criticism has been directed against anti-plague serum, it has 

 been admitted by everyone who has seriously approached the subject 

 that, however disappointing the results of its use on the human subject 

 may be, it manifests definite protective properties when tested on 

 animals. A typical test showing the effect on rats is shown in the 

 annexed Table XIX. 



It will be noted that death occurred in the case of the animals which 

 received the largest dose of serum. The writer has observed similar 

 results in the case of anti-streptococcic serum. Tavel, Krumbein, and 

 Glucksmann also record similar results, and attribute them to the well- 

 known phenomena of "diversion of the complement" easily demon- 

 strated in test tube experiments on bacteriolysis. 



A common experience is to find that animals treated with serum 

 survive till about the tenth day, and then succumb to the disease. This 

 is probably due to the fact that the immune serum has by that time 

 been metabolised and execreted, and that some of the bacilli which have 

 not been destroyed are able to re-infect the animal. 



We have already seen that the antitoxic properties of the serum of 

 the horse " MB." are not of a high order, and probably do not exceed 

 the limits found in normal serum. 



A number of tests were carried out to determine whether the serum 

 possessed bacteriolytic properties. The methods employed and the 

 results obtained are dealt with in the following section. 



Testing Plague Serum for Bacteriolytic Properties. 



A number of methods were employed to ascertain whether 

 bacteriolysis could be demonstrated in the case of anti-plague serum. 

 Neisser's (1904) technique was found to give the most consistent and 

 accurate results. 



Small test tubes of about 10 X I'S cm. are employed. Suitable 

 dilutions of the immune serum are prepared in normal salt solutions, say, 

 I : ID, I : 100, I : looo, etc., and the quantity of serum to be tested is 

 pipetted into each test tube of a series, and to this 0*5 c.c. of fresh normal 

 serum is added to supply complement. Three drops of bouillon are 

 introduced into the mixture, and the volume in each tube is brought up 

 to 2 c.c. A measured quantity of a suitable dilution of the culture is 



(140) 



