Ixxxii 



CLIMATE AND CHANGES. 



for each particular case, and the whole accordingly forms a tangled skein 

 very much more difficult to unravel than we began by thinking it." 



Without going into further details, which can only be looked 

 upon at this stage as greatly theoretical, I desire to add one more 

 remark, and that is : There arises the possible argument that from 

 season to season variation in the direction of the curves and general 

 positions of these means of the isothermal lines occur, and may — and 

 possibly does — take place over Europe and over the whole east-to- 

 west expanse of the Old World. Such movements or occupations 

 may be only temporary, or of greater permanence according to the 

 duration of phenomenal circumstances, such as I have endeavoured 

 to show have taken place during 1902 to 1905. No doubt such 

 circumstances may be accentuated by a natural congestion of any 

 species in any given area, and the surplusage being forced to seek new 

 ground. Perhaps illustrative of this congestion in a particularly 

 "fit" and rapidly increasing species may be instanced the lately- 

 acquired habit of the Starling of nesting among the branches of 

 thickly-planted spruce firs in some portions of their range — a habit 

 at least deserving of mention. This fact has been prominently 

 brought before me by more than one correspondent for the first time 

 in 1905; and conspicuously by Mr. J. Milne's most careful and 

 excellent observations at Auchenblae {in lit., May 26, 1905), and 

 viva voce when I visited him there after that date. 



Other illustrations I have before given in previous volumes of 

 this series. See Woodcock, Dotterel, etc., under species. 



Now, although this may, and to some does, appear self-evident, 

 nevertheless the whole subject is too obscure, for want of real 

 scientific and accurate record, to afford positive data in our present 

 inquiries. What degrees of influence, thus caused, affect — as they 

 surely must affect in some measure — the health and distribution, 

 and even the migration of life, must still remain a mystery, until 

 some more systematic combination of our sciences and practice 

 be inaugurated. But if such a plan could be so inaugurated, 

 there might at least be some hope of solutions to some of the 

 puzzles which exercise both our ornithologists and our meteor- 

 ologists. If all could not thereby be cleared up, some step in 

 advance would surely be assured, and as in all such inquiries, some 

 new " rung in the ladder " be discovered as an upward stepping-place. 



