158 The Naturalist in La Plata, 



of a large hairy caterpillar I have found on dry 

 wood in Patagonia, and which, when touched, emits 

 an intensely nauseous effluvium. Happily it is very 

 volatile, but while it lasts it is even more detestable 

 than that of the skunk. 



The skunk itself offers perhaps the one instance 

 amongst the higher vertebrates of an animal in 

 which all the original instincts of self-preservation 

 have died out, giving place to this lower kind of 

 protection. All the other members of the family 

 it belongs to are cunning, swift of foot, and, when 

 overtaken, fierce-tempered and well able to defend 

 themselves with their powerful well-armed jaws. 



For some occult reason they are provided with 

 a gland charged with a malodorous secretion ; and 

 out of this mysterious liquor Nature has elaborated 

 the skunk's inglorious weapon. The skunk alone 

 when attacked makes no attempt to escape or to 

 defend itself by biting ; but, thrown by its agitation 

 into a violent convulsion, involuntarily discharges its 

 foetid liquor into the face of an opponent. "When 

 this animal had once ceased to use so good a weapon 

 as its teeth in defending itself, degenerating at the 

 same time into a slow-moving creature, without fear 

 and without cunning, the strength and vileness of its 

 odour would be continually increased by the cumu- 

 lative process of natural selection : and how effec- 

 tive the protection has become is shown by the 

 abundance of the species throughoiit the whole 

 American continent. It is lucky for mankind — 

 especially for naturalists and sportsmen — that other 

 species have not been improved in the same direc- 

 tion. 



