MANIFESTED IN THE ANIMAL KINGDOM 81 



Spencer states that a favourable pasture season in 

 the autumn with ewes consequently in good condition 

 is usually followed by a high degree of fertility in the 

 following spring. As the weather most favourable to 

 pasture is hot and moist, and as a hot, moist climate is 

 very relaxing to the nervous system, this rather confirms 

 our hypothesis. But the facts in this connection seem 

 to require more precise observation. 



The pig offers very similar evidence to the horse. The 

 young sow, known to breeders as a " gilt," is generally 

 put to the boar for the first time when from six to ten 

 months old. It is at this time that difficulty is often 

 experienced in getting her to conceive. The period of 

 gestation is four months. She suckles her young eight 

 weeks. When she parts with her litte* a good breeding 

 sow is usually little more than a framework of skin and 

 bone. It is in this condition that she is usually put again 

 to the boar, and if this is done while she is still " poor " 

 from the effects of suckling her previous litter it is seldom 

 that any difficulty is experienced in getting her to conceive 

 again ; and she may go on breeding in this way to the 

 end of her breeding career. If, however, she is allowed 

 to reach a highly-fed condition before being put again 

 to the boar, then trouble is likely to be experienced in 

 getting her to conceive. High condition, as is well known 

 among breeders, is inimical to fertility. It is true that 

 Spencer attempts to establish a distinction between 

 " normal " and " abnormal " plethora, but this is a piece 

 of special pleading. As for the " inverse ratio between 

 the degree of fertility and the cost of individuation," 

 the domestic sow not only conceives best when in low 

 condition, but actually puts on flesh during the period 

 of gestation, so that by the time the young are born 

 she is again in good condition. Thus the amount devoted 



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