68 
D. E. SALMON. 
This important factor is almost entirely lost sight of in the paper 
in question. In all of the work of the Bureau of Animal Indus¬ 
try we rely upon disinfection to destroy the contagion in stables 
and, consequently, as soon as a disinfectant has been scattered 
about a stable, the conditions for a reliable experiment on medi¬ 
ate contagion are destroyed. The disinfection might not have 
been thorough, but there is no way to tell just the degree of its 
action, and, consequently, if no disease follows under such cir¬ 
cumstances you do not know whether to attribute this to the dis¬ 
infection or to some other cause. Hence the problem is compli¬ 
cated, and the results are unreliable as tests of this question. 
The thoroughness of the disinfection in the Shufeldt stables is 
a much debated question and one that probably will never be 
settled. The owners claimed that the stable was frequently 
flooded with water and then well washed with carbolic acid and 
lime water. 
Prof. Law, who looked into this case quite thoroughly, said: 
“ The disinfection of the Shufeldt stables was not exactly a model 
for other disinfectors, but it proved nevertheless to be thorough. 
A small portion of the stables was not even washed with the 
chloride of lime solution. But the great extent of adjacent low- 
roofed sheds well saturated with the chloride kept the whole air, 
even in the unwashed portion, charged with chlorine and chlorine 
compounds, which not only penetrated into the interior of every 
porous substance, but was inhaled day and night by the cattle 
afterward placed in the sheds.” 
My own opinion is that the extremely cold weather had some¬ 
thing to do with freeing these stables from the contagion. There 
are some kinds of contagion which do not resist freezing, but no 
experiments, so far as I know, have been made with pleuro-pneu- 
monia virus to settle this question. But I cannot go into the 
matter more in detail—the question is, can we accept as a test of 
this question the negative results which follow from putting 
cattle into a shed which has been vacated in the dead of a Chicago 
winter and in which disinfectants have been used \ 1 certainly 
should reject such an experiment as absolutely worthless. 
Turning now to the other aspect of the question, let us see 
