Mr. T. H. Huxley on the Method of Palceontoloyy. 43 



v/noji »AT .^ ,^'^ 

 VIII. — On the Method of Paleontology. By Thomas H. Hux- 

 ley, F.R.S., Lecturer on General Natural History at the 

 ^. Government School of Mines, and Fullerian Professor of Phy- 

 . siology R.t. 



There are two perfectly distinct aspects under which Living 

 Beings may be studied — the Physiological and the .Morpholo- 

 gical. On the one hand, every living being exerts certain forces 

 and performs certain acts or functions. It is the object of the 

 physiologist to ascertain the precise mode in which these act* 

 are performed, to refer them as far as possible to the ordinary 

 laws of physics and chemistry, and when, as in many cases, the 

 functions are highly complex, to analyse them into their ele- 

 mentary acts, and to determine by what part of the frame, by 

 what special organs, these are performed. With the form of 

 these parts, with their connexion other than that which is in- 

 volved in their coadjustment towards a common effect, the pure 

 physiologist has no concern. 



On the other hand, every living being has a definite form, 

 and in all the higher living beings this form is complex ; it is 

 made up of a greater or smaller number of lesser parts, each of 

 which has its own definite and appropriate figure. Now it is 

 with these forms, with their mutual relations, with the laws 

 which govern their association, that morphology is alone con- 

 cerned. Although in practice the two branches of biological 

 science are commonly more or less united, yet it would be quite 

 possible to write a complete system of pure physiology without 

 reference to morphology, and of morphology without reference 

 to physiology. They are as distinct as in the mineral world are 

 crystallography and chemistry. To put the case in another way. 

 The different parts of every living being are all mutually related, 

 they are subject to definite laws of correlation, but these laws 

 of correlation are of two kinds essentially independent of one 

 another : there are physiological correlations and there are mor- 

 phological correlations. Thus the teeth and the stomach are 

 physiologically correlated, contributing as they do to the com- 

 mon end of alimentation; and inasmuch as this coadaptation 

 towards a common end is the very essence of physiological cor- 

 relation, the latter has sometimes received the name of rational 

 correlation ; for when the result to which a combination tends is 

 obvious, we commonly imagine we can see the reason for that 

 combination. 



Since the validity of nine-tenths of the science of animal phy- 

 siology involves the admission, that multitudes of the parts of 

 animals are organs working towards a common end, I do not 



