As regards the instability displayed by _colour_, in the insect tribes, when subjected to the action of certain conditions and influences from without, so much has been said in the fourth section of the preceding chapter, that it is unnecessary to repeat it here. True it is that it was then my sole province to discuss the _causes_ which would appear to regulate, in a large measure, the external aspect of the Annulosa; yet the _existence_ of inconstancy, in the several organs and characters involved (with which alone we are now concerned), was, by the nature of the case, implied: so that if the _disturbing element_ was demonstrated, the mere fact that the thing (whatsoever it may have been) _was interfered with_, was surely proved _a fortiori_. I there pointed out the great proneness to a change in hue which divers circumstances are apt to induce; and I particularly instanced proximity to the sea-shore, and other saline spots, as well as an attachment to calcareous districts, as amongst the most powerful of the deranging contingences. In case, however, that any further evidence should be looked for, on this immediate subject, I will quote the following,--relating to the _Bembidium Atlanticum_ of the Madeira islands, which was but just touched upon in that chapter,--as a concluding example of the general effect of physical agents on the colour of these lower creatures. "Throughout all the Madeiran Coleoptera there is perhaps no insect which displays such an extraordinary range of colouring as the present one does; and although it is true that the section of _Bembidium_ to which it belongs is essentially a variable one, yet I am not acquainted with any _Peryphus_ in which the paler patches of the elytra are so remarkably unstable, or which appear to be so completely under the control of external circumstances, as are those of the _B. Atlanticum_: and indeed unless viewed in the mass, we should scarcely be inclined to recognize the same species in the many aspects which it puts on between its extremes. The examination, however, of a very large number of examples, and a careful consideration of the several localities and altitudes in which they were taken, has convinced me that there is unquestionably but a single type of form amongst my entire series, since the whole are so intimately connected, by successive gradations both of outline and colour, that it is perfectly impossible to isolate even a single specimen, or to draw a line of specific demarcation between any two consecutive members of the chain. It will be perceived, by a reference to the diagnosis, that the insect in question passes imperceptibly from nearly a pure green, through a well-defined spotted state, into one which has the elytra almost testaceous,--the paler portions being at last so largely developed as to become confluent, and almost to cover the entire surface. In Madeira proper the darker varieties would seem to be typical; whereas