208 POULTI?Y PRODUCTION 



In this trial, 85 per cent of the fertile eggs set hatched. 

 Eggs destroyed for the purpose of taking temperatures were 

 not counted. 



As the result of careful and rather extended experiment 

 Philips' recommends temperatures of 101° to 102° and 103° 

 F. for the first, second and third weeks of inculjation respec- 

 ti^'ely, using a standing thermometer with the ])ulb on a level 

 with the top of the eggs but not touching them. It is cpiite 

 possible that the temperature requirement varies with the 

 vigor of the breeding stock and one must not necessarily be 

 guided by rule. The chicks should be brought out promptly. 

 As Lamson and Kirkpatrick- remark " one chick hatched on 

 the twentieth day is worth two hatched on the twenty- 

 second." 



Regarding the precise effects of high and low temperatures 

 upon the developing embryo there is little information. 

 Alsop^ found that temperatures between 103° F. and 108° F. 

 produced 90 per cent of the eml)ryos with al)normal nervous 

 systems by the seventy-second hour of incubation or earlier. 

 Of these abnormalities 46 per cent were in the head region 

 and .54 per cent were in the neural tube. In those eggs 

 incubated at 94° F. to 101° F. 07 per cent of the embryos 

 had abnormal nervous systems by the seventy-second hour. 

 Seventeen per cent of these were in the head region and 83 

 per cent were in the nem-al tube. Fggs from the same hens 

 incubated at usual temperatures produced 6| per cent 

 abnormalities by the seventy-second hour or earlier. These 

 abnormalities apparently differed from those noted above. 



It would be interesting to carry eggs incubated at abnormal 

 temperatures for the first seventy-two hours, through the 

 rest of the incubation i)eriofl at normal temperatures to 

 determine what ]>roportion, if any, of these abudrmalities 

 were sul)ser|uently overcome. 



Cooling Eggs. — The custom of cooling eggs during the 

 period of incubation has arisen from a desire to imitate 



' ,Jour. Aru. Assn. Inst, and In\cst. in Fowl llusb , \ol. i\-, No. i). 



' Storr's (Conn.) Bulletin, No. !).^). 



3 The Anatomical IU'for(.l, \o\. \y. No. 5. 



