THE INCUBATION OF HENS' EGGS 



219 



Tabi,!': XXXIV.— Comparative Gains of Early and Late 



Hatohkd Ciih.'ks. (r.)AT\ or Lb\\'is ) 



3.0 



:i 5 



4.5 

 5.5 

 5 

 7.5 



Lot (A). 

 April hatched. 



50 

 50 

 48 

 48 

 48 

 47 



1.47 

 1 81 

 2 . 50 

 3.30 

 4 . 05 



0.34 

 0.69 

 0.80 

 75 



June liiLtchei-I. 



1.0 

 1.5 

 2.5 

 3.5 

 4.5 



50 

 45 

 44 

 44 

 42 



300 

 . 402 

 0,870 



1 210 

 2.100 



0.102 

 4(i8 

 0.3 40 



8110 



4.70 I 65 6.6 , 42 3.000 900 



Mairs' also found tlia.t early-liatchcd chicks grew faster 

 than late-hatched ones, and suggested April 1 as a suitable 

 hatching date for Pennsylvania without making any differ- 

 ence for different classes of chickens. 



Where the falls are quite late, judgment must be used in 

 selecting the date of hatching. It is entirely possible to hatch 

 out pullets so early that they will go through a general molt 

 in the fall, precisely as do the hens, and quit laying until 

 along toward spring. 



Distribution of Incubator Mortality.- — In a Aery careful 

 and interesting study of the time distribution of the mortality 

 of embryos, Payne- found that (19.4 per cent of all the 

 mortality occurred during seven days, namely; the fourth 

 fifth and sixth and the eighteenth to twent}'-fir.st inclusi\c. 

 The irortakty was Ki.- ])er cent during the third to fifth 

 and fS.7 ]>cr I'cnt during the eighteenth to twent\-fir^t. 

 Many of the embryos dying during the latter ])criod were 

 dei'ormeil. A gra])liie presentation of the distribution of 

 embr^'o mortality is shown in Ingure lOl. 



' Pennsylvania Bulletin No. 87. 



^ Jour. Am. A.ysn. Inst, and Inxeat. in Poul. Iluab., \'ol. \'i, No. 2. 



