sect, vi.] INTRODUCTION. 33 



have attempted to solve it by starting from the lumbar plexus, 

 while others have begun from the brachial. In the case of Birds 

 this question is reduced to an absurdity. Which vertebra «>f a 

 Pigeon, which has 15 cervical vertebrae, is homologous with the 

 first dorsal of a Swan which has 26 cervicals ? To decide these 

 questions the only possible appeal is to the facts of Variation, and 

 judged by these facts the whole inquiry comes to an end, for it is 

 seen at once that the expectation is founded on a wrong con- 

 ception of the workings of Variation. No one, as has been said 

 above, would attempt such an inquiry if the series were un- 

 differentiated, for this individuality would not be expected in such 

 a Series ; but to suppose that it does exist in a differentiated 

 Series of parts, is to suppose that with Differentiation the ordinal 

 individuality of the members has become fixed beyond revision. 

 This supposition the Study of Variation will dispel. 



Here, as in the preceding case of the theoretical doctrine of 

 Serial Homology, the current view is far too simple and far too 

 human. Though the methods of Nature are simple too, yet 

 their simplicity is rarely ours. In these subjective conceptions of 

 Homology and of Variation, we have allowed ourselves to judge 

 too much by human criterions of difficulty, and we have let our- 

 selves fancy that Nature has produced the forms of Life from each 

 other in the ways which we would have used, if we had been 

 asked to do it. If a man were asked to make a wax model of the 

 skeleton of one animal from a wax model of the skeleton of 

 another, he would perhaps set about it by making small additions 

 to and subtractions from its several parts; but the natural process 

 differs in one great essential from this. For in Nature the body 

 of one individual has never been the body of its parent, and is no1 

 formed by a plastic operation from it; but the new body is made 

 again new from the beginning, just as if the wax model had gone 

 back into the melting-pot before the new model was begun. 



SECTION VII. 

 Meristic Repetition and Division. 



Before ending this preliminary consideration of ftferism it is 

 right that we should see other aspects of the matter. What fol- 

 lows is put forward in no sense as theory or doctrine but simply as 

 suggesting a line of thought which should be in the minds of any 

 who may care to pursue the subject further or to study the 

 evidence. It is perhaps only when it is seen in connexion with its 

 possible developments that the magnitude of the subject can be 

 fully felt. 



b. 3 



