viii PREFACE. 



not stop here, having for its main end the comparison of these 

 associated modifications and interdependences of organs in all the 

 species of animals. As their degrees of affinity and the characters 

 and circumscription of natural groups are hereby illustrated, this 

 way may be termed ' Zoological Anatomy.' 



In the hands of the anatomist the microscope has been mainly 

 applied to the constituent parts of an organ, called ' tissues ;' and 

 the results of such research, combined with those of chemical 

 tests, constitute a sixth sort of anatomy called ' Histology.' It 

 has been termed i Microscopical Anatomy,' but this is essentially 

 only a more refined method of the scrutiny of organic parts. In 

 so far, however, as ' Histology ' treats of structure according to 

 the proximate tissues common to different organs, it corresponds 

 with the branch of the science which Bichat, its founder, called, 

 loosely, ' Anatomie Generale.' l 



Finally, a seventh Avay in which the highest generalisations in 

 biological science may be aimed at is that wdiich is taken when 

 w r e pursue investigations of form and structure beyond the animals 

 that are to those that have been. Here, however, the anatomist 

 is limited, as a rule, to such tissues and organs as are petrifiable, 

 e.g., corals, shells, crusts, scales, scutes, bones, and teeth ; but he 

 has been stimulated to a degree of minuteness and accuracy of 

 observation in this field of research to which few of the other 

 ways and aims would have led him. In applying the results of 

 such researches to the restoration of extinct species, physiology 

 has benefited by the study of the relations of structure to function 

 requisite to obtain an insight into the food, habits, and sphere of 

 life of such species ; and zoology has gained an immense accession 

 of subjects through such determinations, with improved systems 

 of classification due to the expanded survey of organic nature 

 opened out by ' Palaeontology.' 



The word ' Anatomy ' is still commonly used to signify ' Anthro- 

 potomy,' or ' Human Anatomy.' Almost all begin the study of 

 the science, as medical students, with the dissection of the human 



1 Anatomic Generale, appliquee a la Physiologic, &c, 8vo. 1801. 



