230 
Rahies 
details of these twelve passages in Macacus rhesus, this number of 
passages being considered sufficient to establish our contentions. 
A converse experiment was also conducted to show that the fixed 
virus of the rabbit, when passed through Macacus rhesus, is not altered 
in its virulence either for this monkey or for the rabbit. 
Table III illustrates this point:— 
TABLE III. 
The virus used ivas the ordinary fixed virus of the imssage series and 
obtained Jrom passage rabbit No. 92 of the 15/8/11. 
AVeight of 
Eabbit 
No. of 
the passage 
monkey 
in grammes 
Incub. . , 
Death 
Cultures 
Incub. . , 
DeSth 
1st 
3540 
6/10 
- 
— 
2nd 
2950 
6/9 
- 
— 
3rd 
3000 
6/12 
- 
— 
4th 
1950 
7/9 
- 
7/11 
Not continued further as the point was regarded as sufficiently proved. 
Pasteur (1884) at this conference went on to state:—“It cannot be 
doubted that by passage from monkey to monkey and from the different 
monkeys to the rabbit, the virulence diminishes for these latter animals. 
It is equally diminished for the dog. The dog inoculated from the 
medulla of the fifth monkey had an incubation period of not less than 
58 days although the inoculation had been performed by the method of 
trephining. Other observations of the same nature made on a series 
of monkeys have led to results of the same kind. We are then in 
possession of a method which permits of attenuation of the virulence of 
rabic materials. Successive inoculations from monkey to monkey give 
to the virus, when transferred to rabbits, a power of communicating 
rabies with a progressively lengthening incubation period. Never¬ 
theless if we start from any one of these rabbits to inoculate suc¬ 
cessively other rabbits, the production of rabies in them obeys that law 
of exaltation of the virulence which takes place hy passage from rabbit 
to rabbit and of which we have already spoken. The application of 
these facts places in our hands a method of vaccinating dogs against 
rabies.” 
Our results in the species of monkey which we used are such as to 
lead us to negative the idea of there being any exception in this 
mammal, of the law of exaltation of virulence of sti’eet virus by 
subpassage,'as far as it relates to subdural inoculation. 
