346 Comparative Anatomy — Its History, Aim, and Method 



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Fig. 279 (Left). Johannes Miiller (1801-58). 



Fig. 280 (Right). Thomas Henry Huxley (1825-95). (Courtesy, Locy: "Biology 

 and Its Makers," New York, Henry Holt & Co., Inc.) 



The first half of the nineteenth century was a period of fact-gather- 

 ing. The evolution theory was not under active discussion. Apparently 

 it was accepted by only a very small and mostly silent minority. The 

 comparative anatomy of the period was strongly impregnated with 

 transcendentalism. It was the fashion to search for unity of plan, uni- 

 formity, repetition of similar parts — to try to reduce many things to 

 one thing — and all with little regard for causal explanation. But the 

 need for interpretation was merely somnolent, not dead. The half- 

 century's accumulation of fact built up a state of intellectual high pres- 

 sure which merely awaited something to release it into open demand 

 for interpretations. The work of Darwin and Wallace effected the 

 release. Evolution at once became the chief subject for scientific discus- 

 sion. The weight of Darwin's evidence and the clearness of his reason- 

 ing were irresistible. The forceful writings and lectures of Thomas 

 Henry Huxley (1825-95) greatly strengthened the case for evolution. 

 Within two decades, evolution, in the sense of genetic continuity ac- 

 companied by change in form and structure, came to be the accepted 

 view of the great majority of scientists. But opinions differed, as they 

 still do, in regard to the causal factors in the process of evolution. 



POST-DARWINIAN COMPARATIVE MORPHOLOGY 



The post-Darwinian period is marked, first of all, by the consolida- 

 tion of the grounds for evolution. This was done not so much by making 

 additions to morphologic knowledge as by reinterpretation of the old 

 knowledge. Transcendental anatomy had not been altogether a waste 

 of time. "Archetypes" had served as a useful basis for comparison and 

 analysis of structures. Translation into terms of evolution often re- 



