178 Plvenovxena of Variation and Geographical Distribidion. 



vague intermediate forms as destroying the symmetry of their cabinets. 

 We must therefore consider these cases of excessive variation and in- 

 stability as being thoroughly well established ; and to the objection 

 that, after all, these cases are but few compared with those in which 

 species can be limited and defined, and are therefore merely exceptions 

 to a general rule, I reply that a true law embraces all apparent excep- 

 tions, and that to the great laws of nature there are no real exceptions 

 — that what appear to be such are equally results of law, and are often 

 (perhaps, indeed, always) those very results which are most important 

 as revealing the true nature and action of the law. It is for such rea- 

 sons that naturalists now look upon the study of varieties as more im- 

 portant than that of well fixed species. It is in the former that we see 

 nature still at work, in the ver}' act of producing those wonderful mo- 

 difications of form, that endless variety of color, and that complicated 

 harmony of relations, which gratify every sense, and give occupation to 

 every faculty of the true lover of nature. 



Variation as specially influenced hi/ Locality. 



The phenomena of variation as infiuenced by locality have not 

 hitherto received much attention. Botanists, it is true, are acquainted 

 with the influences of climate, altitude, and other physical conditions, 

 in modifying the forms and external characteristics of plants ; but I 

 am not aware that any peculiar influence has been traced to locality', 

 independent of climate. Almost the only case I can find recorded is 

 mentioned m that repertory of natural history facts, "The Origin of 

 .Species," viz. : that herbaceous groups have a tendency to become 

 arboreal in islands. In the animal world, I can not find that any facts 

 have been pointed out as showing the special influence of locality in 

 giving a peculiar fades to the several disconnected species that inhabit 

 it. What I have to adduce on this matter will therefore, I hope, 

 possess some interest and novelty. 



On examining the closely allied species, local forms, and varieties 

 distributed over the Indian and Malayan regions, I find that larger or 

 smaller districts, or even single islands, give a special character to the 

 majority of their Papilionidse. For instance: 1. The species of the 

 Indian region (Sumatra, Java, and Borneo) are almost invariably 

 smaller than the allied species inhabiting Celebes and the Moluccas. 



2. The species of New Guinea and Australia are also, though in a less 

 degree, smaller than the nearest species or varieties of the Moluccas. 



3. In the Moluccas themselves the species of Amboyna are the largest. 



4. The species of Celebes equal or even surpass in size those of Am- 



