Plewro-Pnetomonia of Cattle. 17& 



Summary. 



The results of the experimental work carried out in order to 

 obtain pure cultures of the organism for use in subsequent work, 

 can be summarised as follows : — 



(1) Martin's broth (reaction -j- 10, Eyre's scale), with the 

 addition of 7.5 per cent, of normal ox serum, is the best medium 

 to employ in order to obtain primary cultures of the organism of 

 contagious pleuro-pneumonia. Growth takes place under aerobic 

 conditions of cultivation. The optimum incubation temperature 

 is 37°C. 



(2) Good growths can be obtained on subculture into Mar- 

 tin's broth, with the addition of either 7.5 per cent, normal ox 

 serum, or normal horse serum, or normal rabbit serum. The 

 most copious growth on subculture, is obtained in Martin's broth 

 plus horse serum, while Martin's broth plus rabbit's serum gives 

 a more copious growth than Martin's broth plus ox serum. 



(3) Following primary inoculation of Martin's broth plus 

 ox serum media with virulent serosity, cultures can be obtained 

 after 3 to 4 days' incubation at 37°C. ; whereas the same sample 

 of virulent serosity diluted and filtered through a Chamberland 

 F. filter does not give a recognisable growth until approximately 

 21 days of incubation at 37°C. have elapsed. 



(4) The organisms in cultures obtained from primary inocu- 

 lation of virulent serosity into Martin's broth plus ox serum are 

 capable of nitration through a Chamberland F. filter candle, pro- 

 vided that the culture is first diluted with Martin's broth (with- 

 out serum) in the proper quantity, i.e., preferably about 1 per 

 cent., but never exceeding 2 per cent. The growth obtained is 

 only recognisable after approximately 21 days following the fil- 

 tration and incubation of the nitrate at 37°C. 



(5) The presence of a growth of the organism in Martin's 

 broth serum media is apparent by the slight opalescence produced 

 in the media after inoculation at 37°C. In order to recognise 

 this opalescence it is imperative that uninoculated tubes of the 

 same broth be incubated along with the inoculated ones. That 

 this opalescence is produced by the growth of a micro-organism 

 can be established by subcultures into other Martin's broth tubes 

 and on to Martin's broth agar, and by the fact that in glucose 

 and maltose Martin's broth media, with the appearance of the 

 opalescence, the reaction of the media is rendered distinctly acid, 

 whereas no change is apparent in Martin's broth, containing sac- 



