THE SCOPE OF BIOLOGY. 97 



ganism exhibits, are of two chief kinds. In order of con- 

 spicuousness, though not in order of time, there come first 

 those ultimate arrangements of parts which characterize the 

 organism in its mature state — an account of which, commonly 

 called Anatomy, is more properly called Morphology. And 

 second, there come those successive modifications through 

 which the organism passes in its development from the germ 

 to the adult form— an account of which is called Embryology. 



The facts of structure which any succession of individual 

 organisms exhibits, admit of similar classification. On the 

 one hand, we have those inner and outer differences of shape, 

 that are liable to arise between the adult members of suc- 

 cessive generations descended from a common stock — differ- 

 ences which, though usually not marked between adjacent 

 generations, may in course of many generations become great. 

 And on the other hand, We have those developmental modi- 

 fications through which such modifications of the descended 

 forms are reached. 



The interpretation of structure, as exhibited in individual 

 organisms and successions of organisms, is aided by two sub- 

 sidiary divisions of biologic inquiry, named Comparative 

 Anatomy (properly Comparative Morphology) and Compara- 

 tive Embryology. These cannot properly be regarded as in 

 themselves parts of Biology j since the facts embraced under 

 them are not substantive phenomena, but are simply inci- 

 dental to substantive phenomena. All the facts of structural 

 Biology are comprehended under the two foregoing sub- 

 divisions ; and the comparison of these facts as presented 

 in different classes of organisms, is simply a method of inter- 

 preting the real relations and dependencies of the facts 

 compared. 



Nevertheless, though Comparative Morphology and Com- 

 parative Embryology do not disclose additional series of con- 

 crete or special facts, they lead to the establishment of certain 

 abstract or general facts. By them it is made manifest that 

 underneath the superficial differences of groups and classes 



