BY T. VERNON WOLLASTON, M.A., F.L.S.   "No compound of this earthly ball Is like another, all in all." Tennyson. LONDON: JOHN VAN VOORST, PATERNOSTER ROW. 1856. "I do not enter so far into the province of the logicians as to take notice of the difference there is between the analytic and synthetic methods of coming at truth, or proving it;—whether it is better to begin the disquisition from the subject, or from the attribute. If by the use of proper media anything can be showed to be, or not to

To make a dry subject entertaining, is impossible; but to render it, at any rate, readable, has been my endeavour in the following pages. How far I have succeeded in the experiment, it is not for me to decide. It having been suggested, by several of my friends, that it might be desirable to bring together into a small compass some of the evidence on Insect variation (with reference to external disturbing causes) which my researches in the Madeira Islands have supplied me with, I have been encour

Page 90, for Pecteropus Maderensis read Pecteropus rostratus . SPECIFIC VARIATION IN THE INSECTA....

A very small amount of information gained by the student in the field of Nature is sufficient to kindle the desire to increase it. The more we know, the more we are anxious to know; though the less we seem to know. It is one of the distinctive privileges of the naturalist that he has to labour in a mine which is inexhaustible: the deeper he digs beneath the surface, the richer is the vein for excavation, and the more interesting are the facts which he brings successively to light. Dive he ever s

Perhaps, judging superficially, climatal causes generally would appear to have more effect on insect development than any with which we are acquainted; yet, powerful as they unquestionably are, experience teaches us that such is not the case. In combination with other modifying principles, hereafter to be noticed, they may be (and probably are) exceedingly important; yet, when taken singly and alone, we have no evidence to show that their consequences are of such primary significance as might be

It is perhaps unnecessary that the action of temporary heat and cold, of an unusual degree, should be considered under a separate head from that of climatal causes generally; nevertheless, since the latter are, in a certain sense, permanent in their operation, it may be thought desirable that I should offer a few words on the effect of sudden exceptions to the ordinary routine of things, such as, for instance, seasons of peculiar intensity. It does not however appear that any very important modi

Before we proceed to inquire to what extent the outward aspect of insects is liable to be controlled by the physical state of the areas in which they severally obtain, it may not be altogether out of place to offer a few reflections on the superiority which some regions possess intrinsically over others, both for the increase and diffusion of the animal tribes. To suppose that all countries within the same parallels of latitude are equally favourable for the development of life (not to mention t

Having in the preceding pages touched upon the subject of insect variability, as the occasional result, to a greater or less extent, of climatal and other influences; let us now proceed to consider the importance of a certain physical condition, which will be found, I believe, on inquiry, to be accompanied by a more decided modifying power than any which we have yet discussed. Every one who has examined the natural history of islands, both in theory and practice, must be aware of the many diffic

Depositâ sarcinâ, levior volabo ad cœlum.— S. Jerome. Having now completed the short task which I had undertaken to perform, I will, in conclusion, offer a few brief comments on the results at which we have arrived, and endeavour to realize to what extent the consideration of them is likely to be found useful, during our inquiries into the general subject of entomological geography. Commencing with the thesis, that specific variation, whether as a matter of experience or as probable from analogy