48 Mr. T. TT. Huxley Vj/i the Method of Palaeontology/, 



It is witli no little surprise, therefore, that in the first volume? 

 he finds, or seems to find, the principle of physiological correla- 

 tion brought prominently forward, in the celebrated ' Discours 

 sur les Revolutions,' as the guide in palaeontology, as the 

 especial means by which the determination of mammalian fos- 

 sils, at any rate, is effected. I say, seems to find ; for, after all, 

 if the master's words be studied carefully, it will be discovered 

 that his followers are more Cuvierian than Cuvier. 



In fact, as I have already particularly pointed out, in a lecture 

 which I recently delivered before the members of the Royal 

 Institution, Cuvier gives up the principle of physiological cor- 

 relation, both explicitly in words and implicitly in practice, 

 as an exclusive guide in palseontological research ; and he ex- 

 pressly admits the necessity of a reference to the laws of mor- 

 phological correlation. ^ 



But while admitting the importance of both methods, tlie 

 physiological and the morphological, he gives to the former by 

 his words a prominence which it by no means has in his practice ; 

 or perhaps I may more justly say, that his phraseology is am- 

 biguous, from his having confounded the two methods together, 

 under the one term of " principe de la correlation des formes 

 dans les etres organises.'' Those who will read carefully from 

 p. 178 to p. 189 (ed. 4, 1834) of the ' Discours,' will find that 

 this confusion exists throughout. Thus, if we take one of the 

 opening passages already cited (p. 1 78) : — 



" Every organized being constitutes a whole, a single, and 

 complete system, whose parts mutually correspond and concur 

 by their reciprocal reaction to the same definitive end. None 

 of these parts can be changed without affecting the others ; and, 

 consequently, each taken separately indicates and gives all the 

 rest." 



The first paragraph here embodies the principles of both 

 physiological and morphological correlation. The second para- 

 graph, however, regards physiological correlation only, and the 

 statement which it contains is not true. We have no evidence 

 to justify us in asserting that no one part can be changed with- 

 out affecting all the others. On the contrary, we have abundant 

 evidence to show that allied species, for instance, differ in only 

 a single character ; which would be an impossibility if a change 

 in one part sensibly affected all the rest. 



Cuvier then goes on to show, in a very beautiful manner, the 

 physiological correlation which exists between the parts of a 

 Carnivore, concluding with the well-known phrase, " in the 

 same way the claw, the scapula, the condyle, the femur, and all 

 the other bones taken separately, will give the tooth, or one 



