GENERAL PRINCIPLES 



OF 



ZOOLOGY 



INTRODUCTION. 



Man's Relation to Other Animals. The man who has 

 learned to observe nature in an unbiassed manner sees him- 

 self in the midst of a manifold variety of organisms, which 

 in their structure, and even more in their vital phenomena, 

 disclose to him a similarity to his own being. This simi- 

 larity meets him among many of the mammals, especially 

 the anthropoid apes, with the sharpness of a caricature. In 

 the invertebrated animals it is not so distinct ; yet even in 

 the lowest organisms, for our knowledge of which we are 

 indebted to the microscope, it is still to be found ; for we 

 can come to understand those vital processes which in 

 our own bodies have reached an astonishing completeness 

 and complexity, only through a thorough investigation 

 of their simplest characteristics. Man is part of a great 

 whole, the Animal Kingdom, one form among the many 

 thousand forms in which animal organization has found 

 expression. 



Purpose of Zoological Study. If we would, there- 

 fore, completely understand the structure of man, we must, 

 as it were, look at it upon the background which is formed 

 by the conditions of organization of the other animals, and 

 for this purpose we must investigate these conditions. To 

 such efforts principally does the scientific knowledge of 

 animal life, or Zoology, owe its origin and continued ad- 

 vancement ; even to-day that object is not fully accom- 

 plished and they should not be neglected by the zoologist. 



