BIOLOGICAL THERAPEUTICS 53^1 



in recoveries of animals affected with blackleg, especially when the in j ec- 

 tion is made before the disease has advanced too far. 



Too strong emphasis cannot be placed upon the proper disposal of 

 the carcasses. They*should not be left to be torn apart and distributed 

 over the country by predacious animals and buzzards, but should be 

 buried deeply where they die, without opening, using quick lime or other 

 strong antiseptic to disinfect the carcass and the place where the body 

 has lain. 



Prevention. 



There is no other biological product used as extensively for the pre- 

 vention of disease as is blackleg vaccine, and no other which has become 

 so well established. The good results that followed its introduction are 

 recognized throughout the United States. In blackleg districts a consid- 

 erable portion of calves are annually vaccinated with this product. 



The available statistical data prove the remarkable reduction of losses 

 from this disease, as a result of systematic vaccination. 



Notwithstanding the tremendous economic saving that has resulted 

 from its use, it must be admitted that blackleg vaccine prepared in the 

 usual pellet or powder form from blackleg infected meat is a compara- 

 tively crude product. Blackleg vaccine as marketed at the present time 

 cannot be accurately standardized; a single dose may contain 100,000 

 or 1,000,000 spores and at other times a much smaller number, or even 

 none at all. Such a variation must naturally result in irregularities of 

 the immunizing action of the vaccine, and it is no doubt due to this fact 

 that direct losses from vaccination and deaths from the natural infection 

 after vaccination cannot be entirely avoided. Nevertheless, blackleg 

 vaccination even as heretofore practiced has given splendid results, 

 though complaints against the reliability of the method are not infrequent, 

 both from veterinarians and stockmen. 



Realizing the shortcomings of the vaccine, investigators have been 

 at work to develop a more uniform product that would avoid losses from 

 vaccination, and at the same time, confer on the animals effective pro- 

 tection against blackleg. 



The investigations revealed that certain germ-free filtrates possess 

 great immunizing properties and further that the injection of such fil- 

 trates into cattle will afford them a protection against the natural infec- 

 tion of blackleg. 



Professor Naoshi Nitta of the laboratory of pathology and bacteri- 

 ology of the Tokyo Imperial University, Japan, has recognized the value 

 of this method of immunization against blackleg, and has developed the 

 procedure to such a state of perfection, that it is now uniformly employed 

 in Japan and Korea. 



In the July, 1918, issue of the Journal of the American Veterinary 

 Medical Association, Professor Nitta published the results of the vac- 

 cinations with blackleg filtrate in Japan and Korea in an article entitled 

 "Investigations on Blackleg Immunization", in which he includes as fol- 

 lows: 



"The filtrate of a pure culture of the blackleg organism confers a 

 high degree of immunity on animals treated and it has been already suc- 

 cessfully used in thousands of cattle in infected districts. It is inexpen- 

 sive, the material for T£WfgitPl^^ti^tMS-(9S^&^ cultures of the organisms 



