GENERATION OF ANIMALS, III. ii. 



to sit on them, deteriorate in their condition, as 

 though they were being deprived of one of their natural 

 endowments. 



Animals reach their perfect development in the 

 eggs quicker when the days are sunny, for then the 

 climate takes a share in the work, concoction being a 

 form of heat : the earth helps in concocting them 

 with its heat, and the sitting bird does exactly the 

 sam^e — she infuses her own heat into them as well. 

 Eggs get spoilt and ouria ° (as they are called) are 

 produced in the hot season more often than at any 

 other, as is to be expected. In hot, sunny weather 

 wines turn sour because the sediment gets stirred up 

 — this is what is really responsible for their being 

 spoilt — and the same happens \vith the yolk in eggs. 

 Sediment and yolk are the earthy part in each respec- 

 tively, and as a result of this earthiness wine becomes 

 turbid when the sediment mixes up with it, and these 

 spoilt eggs also become turbid when the yolk does the 

 same. 



It is only to be expected that this should happen in 

 the case of prolific animals, because it is not easy to 

 pro\ide all the eggs ^\ith their proper amount of 

 heat ; some >\ill get too httle, and some too much ; 

 and too much heat will make them turbid, by causing 

 them to putrefy, as it were. Nevertheless, the same 

 thing occurs with the crook-taloned birds, although 

 they lay but few eggs ; out of two eggs, one mil 

 often turn rotten (ourion), and pretty well always one 

 out of three. They are hot in their nature, and they 

 cause the fluid in the eggs as it were to boil over. 

 The yolk and the white, of course, are of an opposite Deveiop- 

 nature to each other. Yolk congeals in frosty j^cubftlon.^ 

 weather,^ and becomes fluid when heated ; hence it 



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