SPECIES AND THEIR ORIGIN 297 



tiger was the " Yellow cat, variegated with long 

 black stripes." 1 The black (water) oak was the 

 " Maryland oak with leaves three-lobed like the 

 sassafras." 



It is obvious that this was a very clumsy and 

 unsystematic method, if the forms to be described 

 were at all numerous. Particularly was it impossible 

 to be certain whether or not two writers were dis- 

 cussing the same thing. As new forms of animals 

 and plants were discovered the confusion became 

 worse. Finally, in the middle of the eighteenth 

 century, order was brought out of the chaos by 

 Linnseus. This great Swedish naturalist worked 

 out and published a classification of all known 

 forms of animal and plant life, the famous Sys- 

 tema Natures. Not only was each kind or " species " 

 described in a brief " diagnosis," but each was 

 given a double name. Thus, all the members of the 

 Cat tribe were called Felis, and the group was called 

 a genus (plural, genera). Each kind of cat was 

 then given a specific name ; thus, the house cat was 

 called Felis domestica; the lion, Felis leo; the tiger, 

 Felis tigris; the black oak, Quercus nigra, etc., the 

 technical designation of the form being compounded 

 of a generic and a specific name. This binomial 

 nomenclature has been used ever since Linnaeus' 

 time, and affords an elastic and easily intelligible 

 system. Not only are closely similar species grouped 



1 " Felis flava, maculis longis nigris, variegata." L.c. p. 195. 



" Quercus Marilandica, folio trifido ad sassafras accidente" M. 

 Catesby, " Natural History of Carolina," I, p. 19. 1731. 



