THE STUDY OF BIOLOGY. 21 



sisting of but two cavities or chambers : the whale, he finds, has 



warm blood, and a heart constructed on the same type as that of the 



biologist himself, and consisting of four chambers. The fish is 



covered with scales : the whale's body-covering consists typically of 



hairs ; and whilst the fish out of water dies, as a rule, because its 



gills are then removed from the medium from which they derive 



the oxygen for breathing, the whale breathes by lungs, and, as every 



one knows, requires to ascend periodically to the surface of the 



water to inhale the air directly from the atmosphere, like ourselves. 



The whole internal economy of the fish, albeit that it exhibits the 



same general type as that of the whale, is of much less complex 



kind. And, not to penetrate more deeply into the distinctions which 



separate the whale race from the fish tribe, we may lay stress on one 



last fact of primary importance in distinguishing the two animals 



namely, that whilst the fish was developed from an egg which was 



hatched externally to the parent body, the whale was born alive and 



was nourished in its early life by the milk-secretion of its parent 



Now, all of these characteristics infallibly demonstrate to the merest 



tyro in zoology that, so far from a whale being in any sense a fish, it is 



a true " quadruped" or mammal like ourselves. It finds refuge in the 



same class which includes the kangaroos and their neighbours as its 



lowest members or democracy, and apes and man as its aristocrats. 



The whale, in short, is a 'mammal with but two well-developed limbs, 



and occasionally rudiments of two other members ; the two front 



and developed limbs being converted into swimming-paddles or 



" nippers." It is a quadruped modified for an aquatic life, and 



resembles the fish only in the fact that its body is built up on one 



and the same general type, and in its outward modification as a 



tenant of the " vasty deep." Thus clearly do we observe that the 



true position of an animal or plant in the living series can only be 



determined by a reference to the facts of structure. Classification, in 



other words, is the natural termination to the work begun by the 



.anatomist and the student of development. 



Turning to the second question asked by biological science 

 regarding every living being " How does it live?" we find the 

 science of Physiology credited with furnishing the reply to this latter 

 query. Physiology is the " science of functions," a term translatable 

 into meaning that branch of inquiry which shows us how the living 

 mechanism works, and how life is supported in virtue of defined 

 actions which it is the duty of that mechanism to perform. The 

 watchmaker or other artificer who, setting the mechanism he has 

 constructed in motion, professed to instruct us in the manner of its 

 working, would be showing us the " physiology" of the machine 

 just as previously, when describing its structure, he taught us its 

 " morphology." We may go further still, and add, that, without a 



