374 ALBERT C. EYCLESHYMER. 



and the reading recorded. Although a great number of these 

 tests were made and tabulated they were later discarded, owing 

 to wide variations in the hygrometers and the problem attacked in 

 another way. It is of course well known that the egg decreases 

 in weight during incubation and that this is due chiefly to the 

 evaporation. In order to find out definitely how much evapora- 

 tion goes on during natural incubation, thirty-six eggs were 

 weighed each day for twenty days and these weighings tabu- 

 lated. It was found on the average that the egg during natural 

 incubation loses about 1 3 per cent, of its original weight. 



It was also found by experiment that the evaporation could be 

 lessened until the egg lost but 9 per cent of its original weight 

 and still give a healthy chick. It was likewise learned that 

 evaporation could be increased up to about 20 per cent and the 

 eggs give rise to perfect chicks. It would thus appear that the 

 moisture in the incubator should be so controlled that it will 

 allow the evaporation of about 1 3 per cent of the original weight 

 of the egg. 



BIBLIOGRAPHY. 

 Dareste, C. 



'91 Production artificielle des monstruosities. Paris, 1891. 

 Gerlach, M. 



'82 Doppelmisbildungen bei den hoheren Wirbelthieren. 1882. 

 Reamur. 



'49 Art de faire eclore d' el eve en toute saison des oiseaux domestique de toutes 

 especes, soil par le moyen de la chaleur des furnier, soit par le moyen de 

 celle du feu ordinaire. Paris, 1849. 



