320 Manual of Veterinary Microbiology. 



ways at hand efforts have been made to preserve the 

 virus. 



M. Laquerriere showed that in a frozen lung the 

 virus remains intact for one year, at least. 



M. Nocard has quite recently recommended the 

 preservation of the virus by the addition of half a 

 volume of a five per cent solution of carbolic acid 

 and half a volume of pure neutral glycerin. This 

 mixture retains its virulence for months. 



For the purpose of procuring pure virus some have 

 advised its cultivation by direct inoculation in the 

 cellular tissue of the calf and collecting the serosity 

 of the inflammatory engorgement. 



Others again have sought for a means of mitigating 

 the eflects of the natural virus in order to diminish 

 the accidents which result from its use; Pasteur has 

 shown that it is preserved for six weeks in sealed 

 tubes, but, at the same time, becomes so attenuated 

 that it can be inoculated in an interdicted region 

 without exciting fatal lesions. It has also been pro- 

 posed to dilute the virus in water. Dilutions of 1 to 

 50, 1 to 100, and 1 to 500 have yet sufficient activity 

 to produce considerable inflammatory reactions and, 

 therefore, to confer immunity. 



Septic pleuro-pneumonia of calves. 

 This disease occurs in an enzootic form on certain 

 farms, attacking and quickly killing calves while still 

 quite young. The lesions by which it is characterized 

 have some analogy with those of contagious pleuro- 

 pneumonia of larger cattle, but the thickening of the 

 connective tissue septa is less marked and the flow 

 of serosity less abundant, whilst the individual pul- 



