vi.] ON THE STUDY OF ZOOLOGY. 91 



If we were to examine every animal in a similar manner, we 

 should establish a complete body of zoological morphology. 



Again, we investigated the distribution of our type in space 

 and in time, and, if the like had been done with every animal, 

 the sciences of geographical and geological distribution would 

 have attained their limit. 



But you will observe one remarkable circumstance, that, up to 

 this point, the question of the life of these organisms has not 

 come under consideration. Morphology and distribution might 

 be studied almost as well, if animals and plants were a peculiar 

 kind of crystals, and possessed none of those functions which 

 distinguish living beings so remarkably. But the facts of 

 morphology and distribution have to be accounted for, and the 

 science, whose aim it is to account for them, is Physiology. 



Let us return to our lobster once more. If we watched the 

 creature in its native element, we should see it climbing actively 

 the submerged rocks, among which it delights to live, by means 

 of its strong legs ; or swimming by powerful strokes of its great 

 tail, the appendages of whose sixth joint are spread out into a 

 broad fan-like propeller : seize it, and it will show you that its 

 great claws are no mean weapons of offence ; suspend a piece of 

 carrion among its haunts, and it will greedily devour it, tearing 

 and crushing the flesh by means of its multitudinous jaws. 



Suppose that we had known nothing of the lobster but as an 

 inert mass, an organic crystal, if I may use the phrase, and that 

 we could suddenly see it exerting all these powers, what won 

 derful new ideas and new questions would arise in our minds 1 

 The great new question would be, &quot; How does all this take place ? &quot; 

 the chief new idea would be, the idea of adaptation to purpose, 

 the notion, that the constituents of animal bodies are not mere 

 unconnected parts, but organs working together to an end. Let 

 us consider the tail of the lobster again from this point of view. 

 Morphology has taught us that it is a series of segments com 

 posed of homologous parts, which undergo various modifications 

 beneath and through which a common plan of formation is 

 discernible. But if I look at the same part physiologically, I see 



