NATURAL AND ARTIFICIAL INCUBATION 71 



which can be sewed on the basket or pushed up under the 

 outside rim with a case knife. Stiff corrugated cardboard 

 cartons made to hold from one to several sittings may- 

 be bought in which to ship eggs. It is advisable to allow 

 eggs for hatching to remain in one position for about 12 

 hours after they are received, in order to allow the yolk to 

 regain its normal position before the eggs are incubated. 



PERIOD OF INCUBATION 



The period of incubation of several of the different species 

 of poultry is shown in the following table: 



Table I. Period of Incubation for Poultry. 



Within a given class of poultry the period of incubation 

 varies somewhat with conditions. For example, a hatch 

 may run over one or two days in some instances, because 

 the incubation temperature was too low throughout that 

 period, while, on the other hand, the hatch may come off 

 earher than expected on account of a slightly higher temper- 

 ature during the incubation period. If, as the result of an 

 accident, the eggs are chilled or are overheated, the hatch 

 should be continued and the eggs tested after a few days to 

 determine the extent of the damage. There are instances 

 known where chicks have been hatched from eggs left out 

 of the incubator all night, as well as from eggs that have 

 been subjected for a short time to a temperature consider- 

 ably over 103°. Such practices, however, should be avoided, 

 as the chicks from such eggs usually do not grow well. 



PROPORTION OF SEXES 



The average hatch will result in producing approxi- 

 mately 50 per cent of the chicks hatched as males and 50 



