REVIEWS. 293 



The child who stretches out his hand^ and tries how far the 

 impressions of touch, of temperature, and of muscular sense 

 agree with those of sight, has already entered on the path of 

 experimental science. When the form of an animal has been 

 ascertained by such a process, the knowledge of its simplest 

 functions is gained as much by experiment as by observation ; 

 and in the further study of the object, from the roughest 

 descriptive anatomy to the most refined experiments upon 

 the processes of its nervous system, observation and experi- 

 ment must go hand in hand. 



It may suffice for the poet or the painter to see a face in 

 one aspect only, but the zoologist must see it on both sides, 

 must bring every available sense to bear, must measure, and 

 weigh, and test, and thus seek to verify his first impressions. 

 The real contrast is not between physiology as a science 

 of experiment and zoology as one of observation, but between 

 physiology as the study of the functions, and morphology as 

 that of the structure, of living beings — the two, with organic 

 chemistry, completing the comprehensive science of biology. 

 Descriptive or topographical anatomy and histology are 

 merely convenient departments of morphology. Zoology, 

 Mhich once meant the whole science of organisms between 

 man and plants, is now properly merged in biology, since 

 the advance of knowledge has shown that we cannot entirely 

 separate the study of the structure and functions of the 

 so-called lower animals from that of " the animal best known 

 to us," on the one hand, and from that of plants on the other; 

 but the term zoology is still retained, sometimes qualified by 

 the epithet descriptive, to denote a branch of biology almost 

 exclusively confined to determining the species of animals 

 and arranging them in a suitable classification. Now, specific 

 characters are nothing but those anatomical characters which 

 are most easily determined ; and thus it is a mere accident 

 that zoology seems to have most to do with external, and 

 comparative anatomy with the internal organs of animals. 

 Again, a good classification is one of two things : it is either 

 a convenient plan for stating and remembering a multitude 

 of anatomical facts, or else it is based on some general bio- 

 graphical theory, such as creation by type or development by 

 evolution. 



Thus, we see that zoology is only a branch of the general 

 history of organic beings, and animal physiology is no more. 

 All zoology may be divided between morphology and physio- 

 logy ; but just as for convenience we distinguish between 

 descriptive zoology and comparative anatomy, so we may dis- 

 tinguish between the study of the habitat, food, mode of life 



