INCUBATION 
15 per cent. At both stations, incubators without moisture 
ran several per cent. higher evaporation than eggs under 
hens. The conclusions at all stations were that the addition 
of moisture to incubators was a material aid to good hatches 
of livable chicks. 
At Ontario the average evaporation ran from as low as 7 
per cent. At Utah it reached as high as 24 per cent. Now as 
the entire loss of weight is loss of water, the solid contents 
remaining the same, and as the original per cent. of water 
contained in the egg (shell included) is only 65.5, the chicks 
of the two lots with the same amount of solid substance would 
contain water in the proportion of 58.5 to 41.5. Based on the 
welght of the chick, this would make a difference of water 
content of over 25 per cent. 
That human beings or other animals could not exist with 
such differences in the chemical composition of the body, is at 
once apparent. In fact I do not believe that the chick can 
live under such remarkable circumstances. As I have picked 
the extreme cases in the series given, it is possible that these 
extremes were experimental errors, and as in the Utah data, 
no information is given as what happened to the chicks, I have 
no proof that they did live. But from the large number of 
haiches that were recorded below 9 per cent. and above 15 
per cent., giving a variation of the actual water content in the 
chick’s body of about 10 per cent., it is evident that chicks 
do hatch under remarkable physiological difficulties. One ex- 
planation that suggests itself is, that as there is considerable 
variation in evaporation of individual eggs due to the amount 
of shell porosity, and the chicks that hatch in either case may 
be the ones whose individual variations threw them nearer the 
normal. 
By a further study from the Ontario data of the relation of 
the evaporation to the results in livable chicks, it can be 
readily observed that all good hatches have evaporation cen- 
tering around the 12 per cent. moisture loss, and that all lots 
with evaporations above 15 per cent. hatch out extremely poor. 
The general averages of the machines supplied with some 
form of moisture was 35 per cent. of all eggs set, in chicks 
alive at four weeks of age, while the machines ran dry gave 
only 20 per cent. of live chicks at a similar period. | 
Now, I wish to call attention to a further point in connec- 
tion with evaporation. If the final measure of the loss of 
weight by evaporation were the only criterion of correct con- 
ditions of moisture in the chick’s body, the hatches that show 
12 per cent., or whatever the correct amount of evaporation 
84 
