456 ANIMAL BIOLOGY 



Naturally the earliest classifications were utilitarian or more or 

 less physiological — fowl of the air, beasts of the field ; edible, 

 poisonous, etc. But as knowledge increased emphasis was shifted 

 to the anatomical criterion of specific differences, and thenceforth 

 classification became an important aspect of natural history — a 

 central thread both practical and theoretical. Practical, in that it 

 involved the arranging of living forms so that a working catalog 

 was made which required nice anatomical discrimination, and 

 therefore the amassing of a large body of facts concerning animals 

 and plants. Theoretical, because in this process zoologists and 



Fig, 295. — John Ray. 



botanists were impressed, almost unconsciously at first, with the 

 ' affinities ' of various types of animals and plants, and so were led 

 to problems of their origin. (Fig. 297.) 



From Aristotle, who emphasized the grouping of organisms on 

 the basis of structural similarities, we must pass over some seven- 

 teen centuries, in which the only work of interest was done by the 

 herbalists and encyclopaedists, to the time of Ray (1628-1705) of 

 England and Linnaeus (1707-1778) of Sweden. Previous to Ray 

 the term species was used somewhat indefinitely, and his chief 

 contribution was to make the word more concrete by applying it 

 solely to groups of similar individuals which seem to exhibit con- 

 stant characters from generation to generation. This paved the 

 way for the great taxonomist, Linnaeus. (Figs. 295, 296.) 



