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 throughout 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. 
