FORMAL AND FUNCTIONAL STANDPOINTS 305 



thought with the Cuvierian school. It is the cardinal principle 

 of pure morphology that function must be excluded from 

 consideration. This is a necessary and unavoidable simplifi- 

 cation which must be carried out if there is to be a science of 

 pure form at all. But this limitation of outlook, if carried 

 over from morphology to general biology becomes harmful, 

 since it wilfully ignores one whole side of life and that the 

 most important. The functional point of view is clearly 

 indispensable for any general understanding of living things, 

 and this is where the Cuvierian school has -the advantage 

 over the transcendental its principles are applicable to 

 biology in general. 



Geoffrey and Cuvier in pre-evolutionary times well 

 typified the contrast between the formal and the functional 

 standpoints. For Geoffroy form determined function, while 

 for Cuvier function determined form. Geoffroy held that 

 Nature formed nothing new, but adapted existing " materials 

 of organisation " to meet new needs. Cuvier, on the other 

 hand, was always ready to admit Nature's power to form 

 entirely new organs in response to new functional 

 requirements. 



The evolutionists followed Geoffroy rather than Cuvier. 

 They laid great store by homological resemblances, and 

 dismissed analogies of structure as of little interest. They 

 were singularly unwilling to admit the existence of 

 convergence or of parallel evolution, and they held very 

 firmly the distinctively Geoffroyan view that Nature is so 

 limited by the unity of composition that she can and does 

 form no new organs. 



By no one has this underlying principle of evolutionary 

 morphology been more explicitly recognised than by 

 Hubrecht, who in his paper of 1887, after summarising the 

 points of resemblance between Nemertines and Vertebrates 

 which led him to assume a genetic connection between 

 them, writes as follows : " At the base of all the speculations 

 contained in this chapter lies the conviction, so strongly 

 insisted upon by Darwin, that new combinations or organs 

 do not appear by the action of natural selection unless others 

 have preceded, from which they are gradually derived by a 

 slow change and differentiation. 



