242 THE CELL-THEORY 



whatever, within certain Hmits, be the change in external conditions, 

 or whatever pains may be taken to prevent any variation in them. 



Broadly, we may thus state the difference between the subjects of 

 Physical and those of Biological Science : the former, the stone, the 

 gas, and the crystal, have an inertia ; they tend to remain as they are, 

 unless some external influence affect them. The latter, animals and 

 plants, on the other hand, are essentially characterized by the very 

 opposite tendencies. As Reichert well expresses it : 



" All organic bodies, therefore, represent, in relation to one another 

 different and manifold states succeeding one another definitely upon 

 a similar and homogeneous foundation ; they form a common 

 differential series, in which, independently of external conditions, a 

 continual increase in the mutual differences and a diminution of the 

 resemblances, occur.'' (p. 12.) 



Linnaeus seems to have wished to express his insight into this 

 difference between living and dead matter, in his celebrated aphorism : 

 " Stones grow ; plants grow and live ; " but so long as this " and live " 

 was not analysed into its true meaning, the phrase marked the differ- 

 ence, but failed to define it. 



Bichat recognised the independence of action of living beings in 

 another way. All things which surround living beings tend, he says, 

 to destroy them ; but they nevertheless follow out their own appointed 

 course. " La vie est I'ensemble des fonctions qui resistent a la mort.'' ^ 



Now, this faculty of pursuing their own course, this inherent law 

 of change, introduces, it will be observed, an element into the study 

 of living beings which has no analogue in the world of ordinary 

 matter. The latter frequently possesses structure, and may therefore 

 be the legitimate subject of anatomy ; but it undergoes no definite 

 cyclical alterations,''' and, therefore, it offers nothing which corresponds 



' It is amusing to find M. Comte, a mere bookman in these subjects, devoting a long 

 argument (Philosophie Positive, tom. iii. p. 288) to a refutation (?) of what he calls the 

 " profonde irrationalite " of Bichat's definition. As a specimen of the said refutation, we 

 may select the following passage: "Si comme le supposait Bichat, tout ce qui entoure les 

 corps vivans tendait reellement a les detruire, leur existence serait par cela meme radicale- 

 ment inintelligible ; car, ou pourraient-ils puiser la force necessaire pour surmonter meme 

 temporairement un tel obstacle ? " What a question for a positive philosopher ! Does M. 

 Comte doubt his own power to get up from his easy chair, because it is unquestionably true 

 that the action of the whole globe " tends " to retain him in his sitting posture, and because 

 he cannot tell whence he gets the force which enables him to rise ? 



' It is not easy to frame a definition of the differences between living and not living 

 bodies which shall perfectly defy cavil. That in the text — based on the inertia of not living 

 bodies, the internal activity of living bodies — marks the difference strongly but not un- 

 objectionably, for it might be said that a nebula undergoing change would, by this definition, 

 be a living body, and in the next place, it might be urged, how do we know that the activity 



