FROTECTIVE INOCULATIONS. 337 
This secondary virus was very extensively used by Lenglen, a veter- 
inarian at Arras, who communicated his results to the Academy of 
Science at Paris, in April, 1863, and Willems says, in his last pub- 
lished communication, that this is the method which he prefers. It 
is also the method most extensively employed in Australia, into which 
country infectious pleuro-pneumonia was introduced in 1858. It 
quickly spread and has caused enormous losses. The killing of all 
animals, sick or suspected of being infected, was tried for several 
years; but this proved to be ineffectual for stamping out the disease, 
and the sacrifice was so great that this measure of prophylaxis was 
abandoned. 
According to Loir, attention in Australia was called to Willems’ 
method of protective inoculations, in 1861, by a letter from Cape 
Colony published in the journals of Sydney and in Melbourne. The 
method was at once applied both in Victoria and in New South Wales, 
and since that date many thousands of cattle have been inoculated. 
In order to obtain a sufficient supply of virus the method recom- 
mended by Pasteur in 1882 has been followed. This is described by 
Pasteur himself in the following words: 
“With a single lung we may procure sufficient virus to serve for numer- 
ous series of animals. And without having recourse to other lungs this pro- 
vision may be maintained in the folowing manner: It is sufficient before the 
supply of virus is exhausted to inoculate a young calf in the dewlap or in 
the shoulder. The animal dies very promptly, and all its tissues near the 
point of inoculation are infiltrated with serum, which is virulent, and may be 
collected and preserved in a state of purity.” 
Loir prefers to obtain the virus in this way from a calf six to twelve 
months old, during the second week after inoculation, when the tem- 
perature of the animal has gone up to 40° to 42° C., as the virus is 
then said to possess the maximum degree of intensity. This vaccine 
seems to become attenuated in passing through a series of animals by 
inoculation, so that when it has been passed through a series of five 
animals it no longer produces death even when inoculated in the most 
dangerous localities. Loir testifies to the protective value of inocula- 
tions with this virus made in the tail of the animal, and gives the fol- 
lowing example: A few months prior to the publication of his paper 
(1893), about two thousand cows were inoculated with a virus which 
had been passed through a series of five calves. At the moment of 
being driven away they were joined by nineteen other cows not vac- 
cinated. After being on the road for a distance of two thousand kilo- 
metres, the animals arrived at their destination. The two thousand 
vaccinated were in good condition, while eight of the non-vaccinated 
had died of pleuro-pneumonia. 
