24 
Scientific Proceedings (40). 
creased virulence. But in as much as in a number of experiments 
such an excluding action of a first inoculation was not noticeable, 
we are not yet ready to state positively that such an immunizing 
effect of a growing tumor exists. We are however inclined to 
believe that a number of variable factors (especially a variable 
energy of growth of the first and second tumors) are present and 
that such factors complicate the results. In further experiments 
we shall endeavor to analyze such variable factors. 
15 (540) 
Supplementary report on attempts to immunize against 
tuberculosis. 
By J. P. ATKINSON and 0. B. FITZPATRICK. 
[From the Department of Health, City of New York.] 
We have sought to employ the resistance acquired by or 
embodied in the serum of the healthy animal in its life struggle 
against a deadly infection with tuberculosis. 
The depression reaction produced by injections of tuberculous 
serum into animals sensitised with tuberculin, a description of 
which we have already published has led us to this investigation. 
After employing a number of methods for utilizing the serum 
of healthy animals which had been infected with tuberculosis, 
we are duplicating one which seems to have given promising 
results. 
Method 1 — Begun December 2, 1909. The result of this 
experiment was reported at the meeting of the American Associ- 
ation for the Advancement of Science, December 27, 1909. 
One rabbit was given a sensitising dose of 1 c.c. tuberculin 
subcutaneously and beginning two days later this rabbit received 
the following: 
Tuberculous rabbit serum. 
(< <« << 
«i << <( 
<< n << 
<i << << 
<< (< «i 
<< << <« 
A rest of ten days was given the experimental rabbit which was 
Dec. 4, 
10, 
14, 
16, 
18, 
I c.c 
2 C.C. 
