186 G. G. Ileslop: 



It is worthy of note that the positive sera which showed agglu- 

 tination in three and a-half hours in dilutions of 1 in 30, and 

 1 in 35, were sera taken from animals affected with the disease 

 in an acute form. 



The results of agglutination tests under the microscope with 

 dark ground illumination can be conveniently tabulated as 

 follow : — 



Dilutions. 



Number of Cases showing Agglutination in any degree. 



1 in 6 1 ill 10 1 in 15 1 in 20 1 in 25 1 in 30 1 in 35 1 in 40 

 Xnown positive sera -8-8-8-8-7-5-2-0 



(total tested = 8) 

 Known negative sera -8-8-7-6 3-2-0-0 



(total tested = 8) 



No recognisable agglutination takes place under the micro- 

 scope at room temperature until at least one hour after the mix- 

 ture of culture and serum has been made. The agglutination is 

 apparently completed in approximately three and a-half hours 

 after mixing, and the results tabulated above were obtained from 

 readings made three and a-half hours after the mixture of cul- 

 ture and serum had been made. 



The cultures used in these tests had been grown in Martin's 

 l)roth ox serum (Reaction PH=8.4 approximately), and sub- 

 •cultured every seven to eight days until the eighteenth to 

 twentieth subculture stages had been reached. Each subculture 

 at the time it was used in a test was from six to eight days old. 



A live culture was used in each case. 



There is a considerable amount of technical difficulty in the 

 -conduct of microscopic agglutination tests in which dark ground 

 illumination is an essential factor. The fact that the organism 

 of contagious pleuro-pneumonia is of such minute size adds to 

 the difficulty of successfully carrying out such tests. 



Altogether the results of these microscopic agglutination tests 

 are disappointing in that they do not offer a solution of the 

 problem of diagnosing the disease in the living animal. They 

 are of very great interest, however, in that they furnish the first 

 instance in which agglutinins have been demonstrated to occur 

 in the sera of animals naturally infected with contagious pleuro- 

 pneumonia. 



