176 THE BOOK OF A NATURALIST 



It is not the same in the western prairies of 

 North America. Venomous serpents are relatively 

 more abundant there, and grow larger, and their 

 bite is more dangerous. The horse learns to fear 

 them, especially the rattlesnake, on account of 

 its greater power, its sluggish habits and warning 

 faculties. The sound of the rattle calls up the 

 familiar ophidian image to his mind ; and when 

 the rattle has failed to sound, the smell will often 

 serve as a warning ; which is not strange when we 

 consider that even man, with his feeble olfactory 

 sense, is sometimes able to discover the presence 

 of a rattlesnake, even at a distance of several feet, 

 by means of its powerful musky effluvium. The 

 snake-eating savages of Queensland track their 

 game by the slight scent it leaves on the ground 

 in travelling, which is quite imperceptible to 

 Europeans. In the same way the horse is said to 

 smell wolves, and to exhibit instinctive terror when 

 they are still at a distance and invisible. The 

 terror is not instinctive. The horses of the white 

 settlers on some frontier lands, exposed to frequent 

 attacks from savages, smell the coming enemy, and 

 fly in panic before he makes his appearance ; yet 

 when horses are taken from the savages and used 

 by the whites, these too after a time learn to 

 show terror at the smell of their former masters. 

 Their terror is derived from the horses of the 

 whites. The hunter Selous, as a result of ten years 

 of observation while engaged in the pursuit of big 

 game in the heart of Africa, affirms that the horse 



