604 
ANNALES DE L’INSTITUT PASTEUR 
by using animais of the same race, âge and weight, and 
keeping them prévient s to, and aller, inoculation under ielen- 
tical conditions. It is obvions lhat in practice one is obliged 
to be satisfîed with conditions which are only approximately 
similar. The seat of inoculation and the amoimt of dama ge 
donc to the lissues can be made practically constant by due 
attention to details. 
The only two factors which are necessarily variable are the 
number of bacilli and their virulence. 
WiIh the object of simplifying records one may sub-divide 
the development of experimental tuberculous lésions in the 
cobaye into four stages which are determined by the number 
and situation of tuberculous lésions visible to the naked eye. 
These stages are indicated by the lésions produced in a certain 
length of time by subcufaneous injection of l/20lh of a mil¬ 
ligramme of a pure culture of tuborcle bacilli of moderato 
virulence into the inner aspect of one hind leg at the level of 
the fémoro-tibial articulation. 
STAGE 
or 
DEGREE 
TIME 
after inoculation 
IN LEFT HIND LEG. 
O KG A NS AITECIED WITH LESIONS 
visible in an ordinary 
DISSECTION 
1. 
Within 10 days. . . 
Subcutaneous lissue at seat of inoculation, 
adjacent popliteal gland in left leg. 
2. 
10 to 20 days. . . . 
A. Left superficial and deep inguinal 
glands. 
Sacro-lumbar glands. 
B. Retrohepatic gland and spleen in addition 
to above. 
3. 
20 to 35 days. . . . 
Liver, lungs, bronchial glands, suprasca- 
pular glands, cervical glands on both sides 
of the body. 
4. 
35 days and after. 
More complété invasion of the lymphatic 
glands in front of the diaphragm on both 
sides of the body. Right superficial and deep 
inguinal glands and other glands behind the 
diaphragm on the right side of the body. 
It is obvious that the number of stages could be conside- 
rably increased, and that this would allow of the time periods 
being made more definite; four stages seem, however, sulfi- 
cient for general purposes of comparison. It might, however, 
