BIOLOGY m RELATION TO OTHER NATURAL SCIENCES. 439 



tlie oue liaiid those who make it their aim to investigate the actions of 

 the organism and its parts by the accepted methods of physics and 

 chemistry, carrying this investigation as far as the conditions under* 

 which each process manifests itself will permit; on the other, those 

 who interest themselves rather in considering the place which each 

 organism occupies, and the part which it jilays in the economy of nature. 

 It is apparent that the two hues of inquiry, although they equally relate 

 to what the organism does, rather than to what it is, and therefore both 

 have equal right to be included in the one great science of life, or 

 biology, yet lead in directions which are scarcely even parallel. So 

 marked, indeed, is the distinction, that Prof. Haeckel some twenty 

 years ago proposed to separate the study of organisms with reference to 

 their place in nature under the designation of "oecology," defining it as 

 comprising "the relations of the animal to its organic as well as to its 

 inorganic environment, particularly its friendly or hostile relations to 

 those animals or plants with which it comes into direct contact."* 

 Whether this term expresses it or not, the distinction is a fundamental 

 one. Whether with the tecologist we regard the organism in relation 

 to the world, or with the physiologist as a wonderful comjilex of vital 

 energies, the two branches have this in common, that both studies fix 

 their attention, not on stuft'ed aninuils, buttertiies in cases, or even 

 microscopical sections of the animal or plant body — all of which relate 

 to the framework of life — but on life itself. 



The conception of biology which was developed by Treviranus as far 

 as the knowledge of i»lauts and animals which then existed rendered 

 possible, seems to me still to express the scope of the science. I should 

 have liked, had it been within my power, to present to you both aspects 

 of the vSubject in equal fulness; but I feel that I shall best profit by the 

 present opportunity if I derive my illustrations chiefly from the division 

 of biology to which I am attached — that which concerns the hitenial 

 relations of the organism, it being my object not to specialize in either 

 direction, but as Treviranus desired to do, to regard it as part — surely 

 a very important part — of the great science of nature. 



The origin of life, the first transition from non-living to living, is a 

 riddle which lies outside of our scope. No seriously-minded person 

 however doubts that organized nature as it now i)resents itself to us 

 has become what it is by a process of gradual perfecting or advance- 

 ment, brought about by the elimination of those organisms which failed 

 to obey the, fundamental principle of adaptation which Treviranus indi 

 cated. Each step therefore in this evolution is a reaction to external 

 influences, the motive of which is essentially the same as that by which 



* These he identifies with "those complicateft mutual relations which Darwin 

 designates as conditions of the struggle for existence." Along with chorology — the 

 distribution of animals — (I'cology constitutes what he calls liclations-plujiiiohxjh. 

 Haeckel. "Eutwickelungsgang u. Aufgaben der Zoologie," Jcnaisehe Zeitschr. 1869, 

 vol. v, p. 353. 



