140 THE HISTORY OP ANIMALS. [B. TT. 



dened ; but as soon as it is excluded it thickens and becomes 

 hard, unless it is diseased. And eggs have been known to 

 be excluded in the state in which all eggs are at a certain 

 period of their growth ; for they were entirely yellow, as the 

 young bird is afterwards. Such have also been o'bserved in the 

 domestic fowl beneath the diaphragm, where the eggs of the 

 hen are placed, entirely yellow, and as large as eggs usually 

 are. This has been considered ominous. 



5. They are mistaken who say that the hypenemia (barren 

 eggs) are the remains of former acts of sexual intercourse ; 

 for young birds, as fowls and geese, have been frequently 

 observed to lay such eggs without any sexual intercourse. 

 Barren eggs are smaller, not so sweet, and more fluid than 

 fertile eggs, and they are more numerous. If they are placed 

 under a bird, the fluid part never thickens, but both the 

 yolk and the white remain in their original state. Many 

 birds produce these eggs, as the domestic fowl, partridge, 

 pigeon, peafowl, goose, and chenalopex. 1 



6. Eggs are hatched more readily in summer than in 

 winter ; for in the summer the domestic fowl will hatch in 

 eighteen days, but in winter sometimes in not less than 

 twenty-five days. Some birds also are more adapted for 

 incubation .than others. A thunder-storm during the season 

 of incubation will destroy the eggs. What are called cyno- 

 sura and uria (addled eggs) are more frequently produced 

 in the summer. The hypenemia 2 are by some persons called 

 zephyria, because they say that birds receive these winds in 

 the spring. They do the same thing if they are touched 

 with the hand. The hypenemia become fertile ; and eggs 

 that are produced by sexual intercourse are changed to an- 

 other kind, if the hen which contains either hypenemia or 

 fertile eggs has sexual intercourse with another bird before 

 the eggs begin to change from yellow to white, and the 

 hypenemia become fertile, and the fertile eggs produce birds 

 of the nature of the second male. 



7. But if the change from yellow to white has already 

 taken place, neither the barren nor the fertile eggs are al- 

 tered, so as to change to the nature of the/second male. And if 

 the sexual intercourse should be discontinue d while the eggs 

 are small, those which existed previously undergo no chauge } 



1 CEnas tadorna. 2 Eggs formed without sexual intercourse. 



