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Mav, 1900. ] QUEENSLAND AGRICULTURAL JOURNAL. 4:25 
Semond vaccinated 4,000 head of the half-wild range cattle with second 
‘ittcine alone, making the injections behind the shoulder. ‘The subsequent loss 
m blackleg was even smaller than that reported in Europe as resulting after 
“uble vaccination, but it must be remembered that the range cattle of Algeria 
Ne very resistant to blackleg. ' 
Subsequently a stronger vaccine, as recommended by Kitt, was prepared 
it various veterinary institutes—for instance, at Edinburgh, Scotland—but it 
Moved to be too strong. ‘he vaccine was heated for six hours at 90 degrees 
0, and was proved experimentally to be harmless; but in one instance, when 
ed on fifteen head of cattle, it caused five to die in the course of three days, 
'td two more died, three to four weeks after vaccination, from typical blacklee. 
This highly unfavourable result cannot well be explained. — It is generally 
| needed that when the vaccine is strong enough to cause one or more cases of 
Thekleg as a result of the inoculation, the surviving animals must be strongly 
| rtified against subsequent infection. In this case, however, two of the 
Necinated calves died of typical blackleg at a time when, for obvious reasons, 
the disease could not be attributed to the operation. 
This experience caused considerable prejudice against protective vaccination 
top blackleg, which later experiments failed to dispel, and up to the present 
Me the method has never become popular in Scotland and England. In the 
Neantime double vaccination in the shoulder region had been very generally 
‘cepted as preferable to inoculations in the tail. M. Strebel stated in 1892 
“at forty to forty-five animals may be vaccinated in an hour by the former 
Method, and alsu that of a total of 13,022 animals treated by this method only 
jive head, or 0:088 per cent., died directly from the inoculation, while the 
Mmediate loss among cattle vaccinated on the tail amounts to twice as much. 
}9ut of a total of 158,579 vaccinated animals (both methods) 493 head, or 0°31 
‘Per cent., died from spontaneous blackleg—that is, the vaccination had in these 
"ses failed to produce immunity. On the other hand, the loss among 106,787 
"hvaccinated animals amounted to 2,049 head, or 1°92 per cent.—more than six 
‘ines as great as among the vaccinated ones. ‘These results were highly 
‘ttisfactory, and proved that preventive inoculation with attenuated virus was a 
‘fe and effective remedy against the disease. It was furthermore observed 
Mt blackleg occurred with less frequency among the unvaccinated cattle in 
Stures where vaccination was practised to some extent for a number of years. 
is is the natural result from a decrease in the infectious material which is 
| Minarily deposited in pastures where no vaccination'is practised. The fewer 
“ses of blackleg, the less opportunity for reinfecting the ground. 
About 1890 or 1891 Professor Kitt published the results of a series of 
“periments which he had undertaken for the purpose of producing a vaccine 
“hich would confer absolute immunity in a single inoculation and still be 
“onsidered safe. Although the grand total of vaccinations up to that time was 
‘tremely satisfactory, there were several instances recorded where a high 
Tcentage of individual herds had died as a direct result of the vaccination. 
le statistics also indicated that a certain number of the vaccinated animals 
failed to become immunised, and died later from spontaneous blackleg (0°37 per 
| “nt.). The new vaccine prepared by Kitt had been exposed to streaming steam 
fa temperature 98 degrees to 102 degrees C. for about six hours, at the end of 
“hich time the virulent pulverised meat was sufficiently attenuated to be 
‘Noculated in comparatively large doses into guinea-pigs, sheep, and calves 
thout fatal result, while producing a high degree of immunity. The 
"eparation of this vaccine is very simple, but the product varies considerably 
Strength, and before being used in practice it is necessary thoroughly to test 
On a number of sheep. Guinea-pigs are yery unreliable for this purpose, 
3 ree are not easily obtained for such experiments in sufficiently aa 
_ inbers. 
§ This vaccine, known as Kitt’s dry vaccine (to distinguish it from a fluid 
’ccine which he prepared later), was extensively used in many countries in 
_“‘ttope, and according to statisties published in 1898 the results obtained with 
jaa 
