96 STUDIES IN ANIMAL LIFE. 



without having rigorously settled what species is, 

 can lead to no edifying result. 



It is notorious that if you ask even a zoologist, 

 What is a species? you will always find that he 

 has only a very vague answer to give ; and if his 

 answer be precise, it will be the precision of erior, 

 and will vanish into contradictions directly it is ex- 

 amined. The consequence of this is, that even the 

 ablest zoologists are constantly at variance as to 

 specific characters, and often can not agree whether 

 an animal shall be considered of a new species or 

 only a variety. There could be no such disagree- 

 ments if specific characters were definite if we 

 knew what species meant, once and for all. Ask a 

 chemist, What is a salt ? "What an acid ? and his 

 reply will be definite and uniformly the same: 

 what he says all chemists will repeat. Not so' the 

 zoologist. Sometimes he will class two animals as 

 of different species, when they only differ in color, 

 in size, or in the numbers of tentacles, etc. ; at other 

 times he will class animals as belonging to the same 

 species, although they differ in size, color, shape, in- 

 stincts, habits, etc. The dog, for example, is said to 

 be one species with many varieties or races. But 

 contrast the pug-dog with the greyhound, the span- 

 iel with the mastiff, the bull-dog with the Newfound- 

 land, the setter with the terrier, the sheep-dog with 

 the pointer; note the striking differences in their 

 structure and their instincts, and you will find that 

 they differ as widely as some genera and as some 



