INSTINCT AND INTELLIGENCE. 



The latter part of this statement is however called in question 

 by some naturalists. 



31. The marmots pass the greater part of their lives in these 

 dens. They remain there during the night and generally during 

 bad weather, coming out only on fine days, and even then not 

 departing far from their dwelling. While they are thus abroad 

 feeding and playing upon the grass, one of the troop, posted on a 

 neighbouring rock, is charged with the duty of a sentinel, observ- 

 ing carefully the surrounding country. If he should perceive 

 approaching danger, such as a hunter, a dog, or a bird of prey, 

 he immediately gives notice by a long continued whistling or 

 hissing noise, upon which the whole troop instantly rush to their 

 hole. 



Fig. 9. The White-throated Sajou. 



32. There is another instinct worthy of notice, the object of 

 which is always the preservation of the individual, and some- 

 times that of the species, which determines certain animals at 

 particular epochs to undertake long voyages. These movements 

 of migratory animals, as they are called, are sometimes periodic, 

 being determined by the vicissitudes of the seasons, the animals 

 being driven either from higher latitudes to lower by extreme 

 cold, or from lower to higher by extreme heat. In other cases 

 the migiation is determined by the care of providing for its 

 young ; the animal migrating to localities where the food for its 

 offspring abounds, and whence after depositing its eggs it departs 

 126 



