go ZOOLOGICAL SKETCHES. 



any way. To his ear the human voice in its most en- 

 dearing tones is a grunt et pr&terea nihil : you might as 

 well appeal to the affections of a cockroach. You may 

 frighten a pig, a goose, a frog, and even a fly, but you 

 cannot frighten or surprise a sloth. On my last trip to 

 Vera Cruz I procured a pair of black tardos, full-grown 

 and in a normal state of health, so far as I could judge, 

 but after a series of careful experiments I have to con- 

 clude that their instinct of self-preservation cannot be 

 acted upon through the medium of their optic or acoustic 

 nerves. They can distinguish their favorite food at a 

 distance of ten or twelve yards, and the female is not 

 deaf, for she answers the call of her mate from an ad- 

 joining room ; but the approach of a ferocious-looking 

 dog leaves her as calm as the sudden descent of a meat- 

 axe within an inch of her nose. The he-sloth witnessed 

 the accidental conflagration of his straw couch with the 

 coolness of a veteran fireman. War-whoops do not 

 affect his composure. I tried him with French-horn- 

 blasts and detonating powder, but he would not budge. 

 One of my visitors exploded some pyrotechnic mixtures 

 of wondrous colors and odors, but the tardo declined to 

 marvel : he is a nil-admirari philosopher of an ultra- 

 Horatian school. 



He has learned to accelerate his progress on a level 

 surface by sliding on his haunches, using the claws of 

 his forefeet like grappling-hooks, and thus crawled one 

 day into a basket that had been assigned to a nursing 



