18G THE HISTORY OF ANIMALS. [B. VII. 



and if the foetus dies in the fourth or eighth month, they 

 usually die also ; so that not only children born in the eighth 

 month often perish, but their mothers also perish with them. 

 In the same way, the period of conception probably is mistaken 

 by those who have been pregnant more than eleven months ; 

 for in these cases the beginning of the conception escapes 

 the notice of females, for frequently after the uterus baa 

 been distended with flatulence, women have copulated and 

 conceived, and supposed that the former condition in which 

 they observed the usual symptoms, was the commencement 

 of gestation. 



CHAPTEE V. 



1. THE human subject also differs from other animals, as 

 to the number of the perfect offspring produced at a birth. 

 For the human subject differs both from animals which 

 produce but one, and those which produce many; for, 

 generally speaking, and, in most cases, women have but 

 one child at a time, though cases of twins occur frequently, 

 and in many places, as inr Egypt, three or four at a 

 birth have been known in some particular places, as I 

 have observed before. Five at a birth are the most that have 

 been produced. This has been observed to take place in 

 many cases, but in one case only have twenty been pro- 

 duced at four births, for five were born each time, and many 

 of them were reared. In other animals, if the twins are 

 male and female, there is no more difficulty in rearing and 

 preserving them, than if they were both of the same sex. 

 In the human subject there are few cases of twins surviving, 

 when one was male and the other female. 



2. The human female and the mare copulate after con- 

 ception more than any other creatures, for all other females, 

 when they have conceived, fly from the males, except those 

 which, like the hare, become pregnant a second time during 

 gestation. But the mare, having once conceived, does not 

 form a second foetus, but generally produces a single foal. 

 In the human subject it happens sometimes, though rarely. 

 Those which are conceived a long while afterwards never 

 come to perfection, but, from the pain which they cause, 

 destroy the original foetus ; and a case has occurred in 

 which twelve imperfect embryos have been produced at 



