INCUBATION 
theory is that the hen cools the eggs from necessity, not from 
choice. In some species of birds the male relieves the female 
while the latter goes foraging. 
But there is no need to argue the question. Eggs will hatch 
if cooled according to custom, but that they will hatch as well 
or better without the cooling is abundantly proven by the re- 
sults in Egyptian incubators where no cooling whatever is 
practiced. 
Searching for the “Open Sesame” of Incubation. 
The experiment station workers have, the last few years, 
gone a hunting for the weak spot in artificial incubation. Some 
reference to this work has already been made in the sections 
on moisture and ventilation. Before leaving the subject I 
want to refer to two more efforts to find this key to the mys- 
tery of incubation and in the one case at least correct an 
erroneous impression that has been given out. ; 
At the Ontario Station a patent disinfectant wash called 
“Zenoleum” was incidentally used to deodorize incubators. 
Now, for some reason, perhaps due to the belief that white 
diarrhoea was caused by a germ in the egg, this idea of wash- 
ing with Zenoleum was conceived to be a possible solution of 
the incubator problem. In the numerous experiments at that 
station in 1907 Zenoleum applied to the machine in various 
ways was combined with various other incipient panaceas and 
at the end of the season the results of the various combina- 
tions were duly tabulated. The machine with buttermilk and 
Zenoleum headed the list for livable chicks. 
For reasons explained in the chapter on “Experiment Sta- 
tion Work,” the idea of contrasting the results of one hatch 
with one sort with the average results of many hatches of an- 
other sort is very poor science. Feeling that the Station men 
would hardly be guilty of expressing as they did in favor of 
such a method without better reason, I very carefully went 
over the results and compared all machines using Zenoleum 
with all machines without it. The results in favor of Zenoleum 
were less marked but still perceptible. I was somewhat puz- 
zled, as I could see no rational explanation of the relation be- 
tween disinfecting incubator walls and the hatchability of the 
chick in its germ-proof cage. Finally I hit upon the scheme 
of arranging the hatches by dates and the explanation became 
at once apparent. The hatching experiments had extended 
from March to July, but the Zenoleum hatches were grouped 
in April and early in May, when, as one would expect from 
weather conditions, all hatches were running good. After 
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