4 A PRIMER OF BIOLOGY 



term is much more readily understood than defined 

 in so many words, and hence it is fortunate that, 

 for our present purpose, each one may work on his 

 own individual conception of the meaning implied 

 by the word and leave verbal interpretations alone ; 

 a study of the characteristics of living things will 

 furnish us with a basis on which to formulate defini- 

 tions subsequently. Meanwhile, let us begin by 

 taking a summary view of the organisms themselves. 

 Before commencing any detailed study of the 

 subject we must recognise that, if our aim be to 

 Biology, understand the fundamental principles of Biology 

 that is to say, of the science which deals with 

 living things we must study organisms alive, not 

 merely investigate the structure of their corpses ; 

 we must watch the machine at work, not simply pull 

 it to pieces when it is at a standstill. A knowledge, 

 however detailed, of the size, shape, minute structure, 

 chemical composition, mode of manufacture and so 

 on, of the several parts of a marine engine or of a 

 chronometer, would give to one entirely ignorant of 

 the uses of these instruments but a poor idea of the 

 purpose for which they had been constructed, or of 

 the part which each component unit played in the 

 complex whole ; the study of the form and structure 

 of the machine must be accompanied by a study of 

 its mode of action and of the manner in which its 

 different parts co-operate in the performance of its 

 functions. If this be true of apparatus relatively 

 so gross, how much truer must it be of the infinitely 

 more complex and delicate mechanisms we term plants 

 and animals. To understand what an animal or a 

 Morpho- plant really is and how it lives, we have to study 

 phfr 3 sio- d both its structure and the functions carried out by 

 logy. its several parts, in other words, both its morphology 



