What are Animals and Plants ? 2)1 Z 



interplay between what we consider our own body and 

 environing nature. So intimate, in fact, is the connection 

 between each of us and his environment, that it is even 

 difficult to determine, in minute detail, the line of separ- 

 ation between the two. Food, even when swallowed, is far 

 indeed from having become 'the tissue it is destined to 

 renovate.' Even when digested and entering the absorbents 

 which convey it to the blood-vessels which carry it to the 

 intimate tissues of the body, who can say exactly how soon 

 the foreign substance becomes the living being, or precisely 

 when and where it is transformed into our very substance ? 

 It is the same with the streams of air carrying inwards the 

 life-sustaining oxygen and outwards the deleterious vapours. 

 By such agencies the outer world blends with us and we with 

 it. Far from finding any such indubitable evidence of the ex- 

 istence of a ' vital force,' as we have of those phenomena we 

 speak of as * heat,' 'motion,' and 'light,' each living organism — 

 thus viewed purely from the standpoint of physical science 

 — seems, in the words of a distinguished German philosopher, 

 Lotze, only as a place in space where the matter, the forces, and 

 the motions of the general course of nature meet each other in 

 relations favourable for the production of vital phenomena. 

 These phenomena excite our admiration, as do the phenomena 

 of heat and pictorial transmission in that part of space near a 

 lens which is called its ' focus.' Yet the phenomena of the 

 focus are not explained by any pecuhar force common to all 

 ' foci ' (and so comparable with the agency of ' vital force * ), 

 but are scientifically accounted for by light and the agencies 

 of media of different densities, through which it is said to be 

 transmitted. 



The life of an organism may be compared {from the 

 physical science point of view) to the quiet light of a wax 

 candle which seems, to the uninstructed observer, to be the 

 sunple action of what he calls * fire,' while to the man of 



