11 Aug., 1919. J J'otdtri/ Rearing. 469 



reduced cost of working, and this work is likely to be specialized. The 

 average poultry-fanner has usually quite enough work to do as it is, 

 and would gladly avail hini.solf of the services of a reliable mammoth 

 hatchery. 



Composition of the Egg. 



The composition of the eg,^ is as follows: — 



Water . . . . . . 66.7 per cent. 



Protein. . . . . . 12.2 per cent. 



Fat ■ . . . . . . 8.9 per cent. 



Ash . . . . . . 12.2 per cent. 



It will, therefore, readily be seen that the water content is very 

 high — about tAvo-thirds of the total — but the heat supplied during 

 hatching serves to evaporate a considerable quantity, and on this account, 

 in dry atmospheres, the air in the machine must be moistened to prevent 

 too great an evaporation of the moisture in the egg. This is the only 

 reason for the supply of moisture in the incubator. In most of the hot- 

 air types of machines, the hot air is driven down over the eggs, and 

 escapes underneath; consequently, it is a mistake to have the water 

 under the eggs; it should, undoubtedly, be above the eggs, so that the 

 hot air may be moisture-laden when passing over the eggs. The egg^ 

 need not be turned during the first forty-eight hours; but after that, 

 turning should be carried out twice a day, and the eggs cooled once a 

 day till the nineteenth day; after which the machine should be shut up 

 until the hatch is complete. Much harm is done by opening the machine 

 " just to have a look," for in this way the membrane inside the shell 

 is dried and toughened, and increases the chick's task of breaking 

 through. 



Best Eggs to use for Hatching. 



The eggs set in the incubator should be of as nearly an even age 

 as is possible, and preferably not over seven days' old. Those with 

 uneven ends or bands are unlikely to hatch, and, therefore, should not 

 be used. It is impossible to detect with the naked eye either fertile or 

 infertile eggs, even when broken open, but an instrument from America 

 is now on the market which is expected to indicate, to a certain extent, 

 the hatchability of eggs, based more or less on specific gravity. No 

 machine yet invented can determine fertility, although the claim has 

 occasionally been made. 



It is generally believed that the denser the albumen the more 

 nourishment there will be for the developing embryo, and, consequently 

 better prospects of a strong, hardy chicken, but as a moderately dense 

 albumen with a very thick, strong shell would give a similar specific 

 gravity reading to an egg with denser albumen but thinner shell, the 

 tests now being made are likely to be somewhat inconclusive. After 

 the moult the eggs are richest in albumen, which is gradually reduced 

 as the season advances, and there is usually a higher percentage of 

 cockerels in the earlier hatches, but this alone does not necessarily prove 

 that denser albumen means a majority of cockrels. 



