ORGANIC GEOLOGICAL DYNAMICS. 563 



they can be securely made, are of extreme interest in their bearing on 

 geological speculations. 



The means by which plants and animals are now diffused from one 

 place to another, have been well described by Mr. Lyell. 3 And he has 

 considered also, with due attention, the manner in which they become 

 imbedded in mineral deposits of various kinds. 4 He has thus followed 

 the history of organized bodies, from the germ to the tomb, and thence 

 to the cabinet of the geologist. 



But, besides the fortunes of individual plants and animals, there is 

 another class of questions, of great interest, but of great difficulty ; 

 the fortunes of each species. In what manner do species which were 

 not, begin to be ? as geology teaches us that they many times have 

 done ; and, as even our own reasonings convince us they must have 

 done, at least in the case of the species among which we live. 



We here obviously place before us, as a subject of research, the 

 Creation of Living Things ; a subject shrouded in mystery, and not 

 to be approached without reverence. But though we may conceive, 

 that, on this subject, we are not to seek our belief from science alone, 

 we shall find, it is asserted, within the limits of allowable and unavoid- 

 able speculation, many curious and important problems which may 

 well employ our physiological skill. For example, we may ask : how 

 we are to recognize the species which were originally created distinct ? 

 whether the population of the earth at one geological epoch could 

 pass to the form which it has at a succeeding period, by the agency of 

 natural causes alone ? and if not, what other account we can o-ive of 



7 o 



the succession which we find to have taken place ? 



The most remarkable point in the attempts to answer these and 

 the like questions, is the controversy between the advocates and the 

 opponents of the doctrine of the transmutation of species. This ques- 

 tion is, even from its mere physiological import, one of great interest ; 

 and the interest is much enhanced by our geological researches, 

 which again bring the question before us in a striking form, and on a 

 gigantic scale. We shall, therefore, briefly state the point at issue. 



Sect. 3. Question of the Transmutation of S}Jecies. 



WE see that animals and plants may, by the influence of breeding, 

 and of external agents operating upon their constitution, be greatly 







'Lyell, B. iii. c. v. vi. vii. 4 B. iii. c. xiii. xiv. xv. xvi. 



