,4 INTEODUCTOEY. 



late Andreas Wagner. This reptile he declares "to he a still 

 nearer approximation to the missing link between reptiles and 

 birds," thus narrowing the gap between the two classes. 



While we think it proper to point to these structural resem- 

 blances of one class of the animal creation to others very different 

 in their external appearance, it is necessary to guard ourselves 

 and our readers from adopting the inferences sometimes deduced 

 from them ; that " these infinitely diversified forms are merely 

 the final terms in an inxmense series of changes which have been 

 brought about in the course of immeasurable time, by the operation 

 of causes more or less similar to those which are at work at the 

 present day." Domestication and other causes have no doubt 

 produced changes in the form of many animals ; but none from 

 which this inference can be drawn, except in the imagination of 

 ingenious men who strain the facts to support a preconceived 

 hypothesis. In spite of the innumerable forms which the pigeon 

 assumes by cross-breeding and domestication, it still remains a 

 pigeon ; the dog is still a dog, and so with other animals. Nor 

 does it seem to us to be necessary, or calculated to advance our 

 knowledge in natural history, to form theories which can only 

 disturb our existing systems without supplying a better. Systems 

 are necessary for the purpose of arrangement and identification ; 

 but it should never be forgotten that all classifications are artificial 

 — a framework or cabinet, into the partitions of which many facts 

 may be stowed away, carefully docketed for future use. " Theories," 

 says Le Vaillant, "are more easily made and more brilliant probably 

 than observations ; but it is by observation alone that science can 

 be enriched." A bountiful Creator appears to have adopted one 

 general plan in the organization of all the vertebrate creation ; 

 and, in order to facilitate their study, naturalists have divided 

 them into classes, orders, and genera, formed on the difierences 

 which exist in the structure of their vital functions. The advan- 

 tages of this are obvious, but it does not involve the necessity of 

 fathoming what is unfathomable, of explaining what is to man 

 inexplicable in the works of Gon.* 



* This, however, is a subject upon whicli naturalists of the highest rank hold 

 diiferent opinions, many of those most highly qualified to form a correct judgment 

 advocating the tenets propounded hy Mr. Charles Darwin. — Ed. 



