BIOLOGY IN RELATION TO OTHER NATURAL SCIENCES. 437 



be to .study tlie forms and phenoineiui of life, its ori,i;iu, and tlie condi- 

 tions and laM s of its existence, and embodied ^iiat Mas known on tliese 

 subjects in a book of seven volumes, wLicli lie entitled Biology, or the 

 rhilosophy of Li v in y Nature. For its construction the material was 

 very scanty, and was cbietly derived from the anatomists and physiolo- 

 gists. For botanists were entirely occupied in completing the work 

 which Liunanis had begun, and the scope of zoology was in like man- 

 ner limited to the description and classification of animals. It was a 

 new thing to regard the study of living nature as a science by itself, 

 worthy to occupy ai)lace by the side of natural philosophj , and it was 

 therefore necessary to vindicate its claim to such a position. Trevira- 

 nus declined to found this claim on its useful applications to the arts 

 of agriculture and medicine, considering that to regard any subject of 

 study in relation to our bodily wants — in other words, to utility — was to 

 narrow it, but dwelt rather on its value as a discipline and on its sur- 

 passing interest. lie commends biology to his readers as a study which, 

 above all others, " nourishes and ]uaintains the taste for simplicity and 

 nobleness,- which affords to the intellect ever new material for reflec- 

 tion, and to the imagination an inexhaustible source of attractive 

 images." 



Being himself a mathematician as well as a naturalist, he approaches 

 the subject both from the side- of natural philosophy and from that of 

 natural history, and desires to found the new science on the funda- 

 mental distinction between living and non-living materials. In discuss- 

 ing this distinction, he takes as his point of departure the constancy 

 with which the activities which manifest themselves in the universe are 

 balanced, emphasizing the impossibility of excluding from that balance 

 the vital activities of plants and animals. The difference between vital 

 and physical processes he accordingly finds, not in the nature of the 

 processes themselves, but in their co-ordination; that is, in their adapt- 

 edness to a given purpose, and to the peculiar and special relation in 

 which the organism stands to the external world. All of this is 

 exi)ressed in a proposition difficult to translate into English, in which 

 he defines life as consisting in the reaction of the organism to external 

 influences, and contrasts the uniformity of vital reactions with the 

 variety of their exciting causes.* 



The purpose which I have in view in taking you back as 1 have done 

 to the begiuing of the century is not merely to commemorate the work 

 done by the wonderfully acute writer to whom we owe the first scien- 

 tific conception of the science of life as a whole, but to show that this 

 conception, as expressed in the definition I have given you as its founda- 

 tion, can still be accepted as true. It suggests the idea of orgdnism as 

 that to which all other biological ideas must relate. It also suggests, 



*"Lel)eu bestflit in der Gleicbformigkeit der Reaktioiien bei uugleiclifijrmigeii 

 Eiuwirkiingeii der Aiissoiiwclt." — Treviraiiiis, Bioloyie vdcr I'hilosophie der hhenden 

 Natut; Gotteugen, 1802, vol. i, p. 83. 



