INCUBATION 
allowing for this error Zenoleum appeared as harmless and 
meaningless as would the Atter of Roses. 
The second link after the missing link of incubation to 
which I wish to call your attention also occurred at the On- 
tario Station. The latter case, however, is happier in that no 
unwarranted conclusions were drawn and that an interesting 
bit of scientific knowledge was added to the world’s store. 
The conception to be tested was an offshoot from the carbon 
dioxide theory. You will remember at the Utah Station the 
idea was that carbon dioxide was to dissolve the shell so the 
chick could break out easier. 
At the Guelph Station the conception was that the carbon 
dioxide might dissolve the lime of the shell for the chick to 
use in “makin’ hisself.” As an egg could not be analyzed 
fresh and then hatched, a number were analyzed from the 
same hens and others from those hens were then incubated 
with the various amounts of carbon dioxide, buttermilk, Zeno- 
leum, and other factors. The lime content of the contents of 
the fresh egg averaged about .04 grams. At hatching time the 
lime in the chick’s body averaged about .20 grams and was 
always several times as great as the maximum of the eggs. 
Clearly calcium phosphate of the chick’s bones is made by 
the digestion of the calcium carbonate from the shell and its 
combination with the phosphorus of the yolk. Certainly a re- 
markable and hitherto unexplained fact. The amount of lime 
required is not great enough, however, to materially weaken 
the shell, but, of course, the process is vital to the chick as 
bones are quite essential to his welfare, but it is an “inside 
affair’ of which the three-tenths of one per cent of carbon 
dioxide incidentally present under the hen is entirely irrele- 
vant. 
A further observation made by the investigator is that the 
chicks which obtained the lowest amount of lime were abnor- 
mally weak. As long as we are powerless to aid the chick in 
digesting lime this fact, like the other, belongs in the field of 
pure, rather than applied science. I think that we are safe in 
saying that the weakness caused the shortage of lime rather 
than vice versa; if the writer remembers runts in other ani- 
mals are usually a little short of bone material. 
The chemist of the station is to be given special credit for 
not jumping at conclusions. In the summary of this work he 
states: “There is apparently no connection between the 
amount of lime absorbed by the chick and the amount of car- 
bon dioxide present during incubation.” 
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