312 POULTRY BREEDING AND MANAGEMENT 



that there was a gradual increase in the ash or lime con- 

 tents of the chick, and that the chick was able to break 

 through the shell with strength derived in part from the 

 shell itself. It was also found that the chick contains con- 

 siderably more lime than the contents of the egg itself. 

 Without the mineral elements of the shell the chick would 

 be unable to grow its frame or skeleton. The shell there- 

 fore has a vital function to perform in the hatching 

 process, in the development of the chick. Moisture with 

 carbon dioxide does not merely weaken the shell so the chick 

 will be able to break through, but the dissolved lime of the 

 shell goes to assist in the formation of the chick and de- 

 termines to a certain extent the future strength and vitality 

 of the fowl. 



But is not the moisture within the egg sufficient for this 

 purpose? With certain machines, or those that gave over 

 30% better hatches with supplied moisture than without, 

 the development of the chick was more complete, there was 

 more ash, phosphorus and protein in the chicks hatched by 

 the machines that were supplied with moisture. The im- 

 portant point brought out here is that the chemical com- 

 position of the chick, its strength and vitality, is influenced 

 by the moisture in the machine. 



It is highly important that the incubator operator should 

 understand the moisture requirements for best chick de- 

 velopment and that he should be able to test the machine 

 for moisture. 



There are other methods of determining the amount of 

 moisture in the machine. Thermometer makers have de- 

 vised different instruments, usually called hygrometers, 

 for determining the humidity of the incubator. Some of 

 these are successful, others are not. When properly con- 

 structed they answer the purpose. The percentage humidity 

 as shown by the hygrometer should average about 60%. 



