THE STUDY OF STRUCTURE. 333 



which we call cells. We get the help of microtome 

 and microscope, of fixing and staining re-agents, and 

 work on until we see the intricate structure of each 

 house, the furnishings and inhabitants of each cell. 

 We try to work back again to the unity which we 

 have taken to pieces; we compare organism with 

 organism and detect their relationships; we compile 

 a census and construct a genealogical tree.* 



FOUNDATIONS OF MOBPHOLOQY. 



Although there were untiring and keen-sighted 

 comparative anatomists in the eighteenth century 

 such as John Hunter and Vicq d'Azyr the modern 

 period may be fairly dated from the work of Cuvier 

 and Goethe, who, though almost antithetic in their 

 outlook on nature, may be called the joint-founders 

 of comparative morphology. 



To Georges Cuvier (1769-1832) the science owes 

 much, not only for his rich accumulation of anatom- 

 ical description, but for his attempt to give an 

 anatomical basis to classification, for his appreci- 

 ation of the value of fossils, and for his insistence 

 on the correlation of parts. The idea expressed in 

 the phrase " the correlation of parts " is now fa- 

 miliar: the organism is no haphazard aggregate of 

 characters, but a unified integrate. Part is bound 

 to part, so that if the one varies the other varies with 

 it. In short, " there are many members which are 

 members one of another, in one body." It must be 

 confessed, however, that Cuvier tended to exaggerate 

 the value of his guiding principle, and that he did 

 not appreciate its full significance as that has ap- 



* See J. Arthur Thomson, The Humane Study of Natural 

 History, Humane Science Lectures, Bell, London, 1897. 



