﻿STUDIES IN PLAGUE IMMUNITY. 255 



Table No. X. — Tests of the agglutinating value of human immune sera — Cont'd. 



Case No. 



XV 



XVII 



XVIII 



XIX 



XX 



XXI 



XXIII 



XXIV 



XXV 



XXVI 



XXIX 



XXXI 



XXXIII 



Plague case . 



Plague 



autopsies 



I and II. 



Manner of inoc- 

 ulation. 



One agar slant 

 "Pest A viru- 

 lent." 



Dilutions. 



-do„ 



_do. 



_do. 



_„_do. 



_do. 



_do. 



1:2; 1:5; 2 con- 

 trols (no serum) 



_do. 



Control normal 

 human serum, 

 1:2; 1:5. 



1:2; 1:5; 2 con- 

 trols (no serum). 



—.do 



—do 



Control normal 

 human serum, 

 1:2; 1:5. 



1:2; 1:5; 2 con- 

 trols (no serum) 



__-_do. 



„do_ 



__do. 



Results and remarks. 



After 1 hour and 10 minutes a flocculent 

 precipitate began to appear in the dilu- 

 tion of 1 : 10. (Compare with Case IX 

 reaction with normal serum.) Dilution 

 1 : 2 negative. 



All negative after 1 hour. After 16 hours 

 moderate sediment in dilution of 1 : 5. 



Both negative after 1 and 16 hours. 



Exactly the same results as with Serum 

 XVII. 



All negative after 1 hour. In Case XXI 

 slight precipitate in dilution of 1 : 5 after 

 3 hours. 



All negative after 1 hour. 

 Negative after 1 hour. Slight precipitate 

 in dilution of 1 : 5 after 3 hours. 



All negative after 1 hour. Sediment in 

 dilution of 1 : 5 after 16 hours. 



All negative after 1 hour. 



Do. 

 . Do. 



A careful study of the above table brings us to the conclusion that in 

 the majority of the instances no traces of agglutinins could definitely be 

 demonstrated. In a few cases they perhaps were present in very small 

 amounts. 



In concluding the remarks on agglutination it may again be emphasized 

 that excessive precautions must be taken to distinguish between pseudo 

 and true agglutination in pest, and that apparently only in the organism 

 highly immunized against plague infection do the agglutinins become 

 developed in sufficient quantity to be of any practical importance either 

 in the diagnosis of the infection or in the demonstration of the presence 

 of an immunity. It also would appear from these experiments that 

 the development of the anti-infectious substances in a plague immune 

 serum is quite independent of the development of the agglutinins. 



