214 POULTRY PRODUCTION 



intake pipes which extended outside the building, and were 

 so arranged that there was a continuous current of fresh 

 air passing into the egg chamber. Eggs from the same hens 

 were placed in each machine. The former hatched 44.3 

 per cent, of fertile eggs while the latter hatched 85.7 per 

 cent. 



While the foregoing shows unmistakably that there is a 

 ventilation problem it does not solve it. Common expe- 

 rience rather than experimental evidence must be depended 

 on in formulating our practice in ventilation. This is done 

 in the suggested routine of management (see page 221). 



Position of the Egg. — It is generally understood among 

 poultrymen that the position of the egg during the period 

 of incubation has a profound influence upon the development 

 of the chick. It is a matter of common knowledge that the 

 head of the chick normally develops at the large end of the 

 egg. As a usual thing, both in the nest and in the incubator, 

 the large end of the egg is uppermost. This is caused by 

 the shape of the egg itself and possibly by the lessening of 

 the specific gravity of the large end as incubation proceeds, 

 due to the increasing size of the air cell. 



Not infrequently, however, chicks develop with the head 

 directed toward the small end. The cause of this, it is 

 asserted, is allowing the egg to rest in the nest or incubator 

 with the small end uppermost. Definite information on this 

 point is scarce. Eycleshymer,' after conducting experiments 

 which did not involve as large numbers as we could wish, 

 came to the conclusion that the "position of the egg is a 

 factor of little or no importance in natural incubation." 

 He further concluded "that when the supply of good fresh 

 air is inadequate the oblique position of the egg, thereby 

 bringing the embryo in closer contact with the air chamber, 

 is decidedly advantageous. Where there is an abundant 

 supply of fresh air, there is but little to be gained through 

 placing eggs obliquely." Where plenty of tray room is 

 allowed, most of the eggs will be found to assume a position 

 that is slightly oblique. 



' Biological Bulletin, May, 1907. 



