THE FLOCKS AND HERDS 147 



progeny seems to infuriate them in a curious manner. One 

 sow which I owned killed three successive litters ; another fine 

 animal of the Berkshire breed, a very amiable, indeed affec- 

 tionate, creature, was carefully watched at the time she first 

 bore young, precautions being taken to prevent her from 

 harming them ; she would willingly allow them to suckle, 

 provided she did not see them, but the moment she laid her 

 eyes upon them she was seized with the strange fury. 



Although this singular perversion of the natural instincts 

 of maternity sometimes occurs among the pigs which are 

 allowed to roam together in herds, it seems to be far more 

 common in those conditions where the animals are confined 

 in pens without contact with their kind, and where they have 

 no chance to recognize the young as members of their species 

 or to acquire that interest in them which they would gain in 

 the society of the herd. It is also clear that this maniacal 

 habit is inherited ; according to my observation it is common 

 among the Berkshire, and relatively rare in other less special- 

 ized varieties. 



The intelligence of the pig is also shown in the readiness 

 with which the creature changes its habits to meet varied 

 environments. Thus the pigs which range the woods in the 

 western and southern parts of the United States have learned 

 to catch the crawfish which abounds in the shallow streams in 

 those parts of this country. They will wade up a brook, 

 turning over the stones and- driftwood as they go, catching 

 with a quick movement the crustaceans which they have thus 

 dislodged from their cover. Along the shores of the Bay of 

 Fundy, the pigs, accustomed to follow the tide out, picking 

 the chance food which is thus exposed to them, have learned 

 carefully to avoid the risk of being caught by the returning 



