GENERATION OF ANIMALS, IV. vi. 



are used to hard work. The reason is that the effort 

 of working uses up the residues, whereas sedentary 

 women have a great deal of such matter in their 

 bodies owing to the absence of effort, as well as to 

 the cessation of the menstrual discharges during 

 gestation, and they find the pains of delivery severe. 

 Hard work, on the other hand, gives the breath 

 {pneuma) exercise, so that they can hold it ° ; and it 

 is this which determines whether delivery is easy or 

 difficult. All these things, then, as we have said, are 

 in their way factors producing the difference in gesta- 

 tion as between women and the other animals ; but 

 the chief one is that whereas in some animals there 

 is but little menstrual evacuation, and in others no 

 \isible evacuation at all, in women it is greater in 

 volume than in any other animal ; and the result 

 of this is that when it is not being discharged o\^-ing 

 to pregnancy it causes them trouble (and indeed even 

 apart from pregnancy, when the menstrual discharge 

 fails to take place diseases are the result) ; and most 

 women are troubled in this way rather more at the 

 beginning, just after they have conceived, because 

 although the fetation is able to prevent the evacua- 

 tion, yet as it is so small it does not at first use up any 

 amount of the residue ; afterwards, when it does take 

 up some of it, it relieves the trouble. In the other 

 animals, however, as there is but little of it, its amount 

 is just right for the growth of the embryos ; and as 

 the residues which obstruct the nourishment get used 

 up, the animals are in better physical condition. The 

 same applies to water-animals and to birds. The 

 reason why some animals are no longer in good 



is supplied bv the holding of the breath." Cf. also 3/../. 

 703 a 18, 9 ; P. A. 659 b 18, 667 a 29 ; and App. B §§ 22 ff. 



463 



