THE INCUBATION OF HENS' EGGS 217 



liour Ixitli (la\' and ini;iit, ami that the}' were coiiiiik'ti'ly 

 I'dtated as many as ten times in two iiours. 



Such observations as have been reported show that in 

 artificial incubation fairly frequent turnings increase the 

 hatching power of eggs. Eycleshymer' found that where 

 eggs were unmoved during the incubation period but IT) ])cr 

 cent of fertile eggs hatched. A very large proportion of the 

 fertile eggs that failed to hatch did so because in the early 

 stages the embryo, or in the later stages the allantois, had 

 adhered to the shell. It is assumed that this could have been 

 largely overcome by turning. 



Eggs from the same hens that were turned at (i a.m. and 

 6 P.M. gave a hatch of 58 per cent of fertile eggs. In this 

 same connection, Jackson^ kept a record of 1350 eggs, half 

 of which were turned twice daily during the incubation 

 period, while the remainder were unturned. These eggs 

 were distributed in ecjual lots through several different 

 incubators. Although the group of eggs that were turned 

 twice daily contained six more infertile eggs than the otiier 

 group, (36 per cent of all eggs set that were turned twice 

 hatched, while but 59.8 per cent of the unturned eggs gave 

 living chicks. 



I'ayne' found that eggs turned four to six times daily 

 (luring incubation in March and A])ril hatched from 4 to 22 

 ])cr cent better than eggs turned twice daily, with an average 

 (.if about 10 per cent. Eggs handled in the same manner in 

 May and .lune showed no advantage in the extra turnings. 

 lie also found that the per cent of defonucd chicks was 

 reduced during March and April by the extra turning, but 

 not in May and June. 



In practice the eggs should be turned as frecjuently as 

 possible. In most cases this will be three times daily — 

 morning, noon, and night. 



Date of Hatching. — The proper date for hatching chicks 

 depends upon local climatic conditions and the breed being 

 hatched. The Mediterranean breeds may be hatched 



1 Biological Bulletin, May, 1907. ' Pennsylvania Bulletin No. 120. 



■• Paper ix'ad before Thirteen Annual C'on\'ention of Aniencim .V.^.sneia- 

 tion of Instructory and In\'esfigators; in Poultry Husbandry, I'J20. 



