INTRODUCTION. 3 



tion, which has its value only in facilitating the discovery or demon- 

 stration of facts. 



Anatomy assumes a very different character so soon as the 

 knowledge of facts is only its means, and its aim the conclusions 

 which can be drawn from an assemblage of such facts ; the facts of 

 individual phenomena being regarded not by themselves exclusively, 

 but being brought into relation with one another. This happens 

 when what is alike in the organisation of different organisms is 

 made the object of search, and when the facts thus acquired are 

 compared. Anatomy thus arrives at scientific results, and shapes 

 the results of inductive inquiry into deductive conclusions. Thus it 

 becomes Comparative Anatomy. Its method is synthetical. The 

 analyses of Descriptive Anatomy (Anthropotomy as well as Zootomy) 

 provide the basis for it ; they are consequently not only not excluded 

 from Comparative Anatomy, but are most closely embraced and 

 logically permeated by it. The more careful the sifting of facts, 

 the surer the basis of comparison. Empiricism is thus the first 

 requisite, and abstraction is the second. Abstraction has no basis 

 without pre-existing empiricism; and empiricism by itself is, from 

 the scientific point of view, a mere stepping-stone to real knowledge. 



§ 3. 



The task of Comparative Anatomy is the morphological ex- 

 planation of the phEenoinena of form met with in the organisation of 

 the animal body. Comparison is the method which serves for the 

 performance of this task. It shows the way which scientific investi- 

 gation has to go, and which it is necessary to know in order to avoid 

 disjointed and fruitless labour. The comparative method seeks 

 to test, in series of organisms, the morphological results of the 

 observation of the organs of the body, places together similar 

 characters, and separates the dissimilar from them. Thus it takes 

 into consideration everything which can in any way be looked at 

 as the result of anatomical observation : relation to other parts of 

 the body, form, number, extent, structure, and texture. It thus 

 collects series of stages for the several organs, in which the extremes 

 may be so far different from one another as not to be recognised, 

 but which are united to one another by numerous intermediate steps. 



It is clear, in the first place, from the existence of various forms 

 of one and the same organ, that the physiological value of an organ 

 in different stages is not by any means the same, but that an organ, 

 as its anatomical characters are modified, may come to have very 

 different functions. The exclusive consideration of their physio- 



b 2 



