and Intensity of Temperature, Economy of Heat, &c., in the Use of Carbonaceous Fuel. Column 14, multiplied by the excess of temperature over that of the atmosphere at which the waste gases escape to the chimney, gives the loss of heat in lbs. water heated 1°, for every lb. of carbon used: which loss increases with the terminal temperature, and with the draught as given in columns 2 and 4. 200° Term. 300° Term. 400° Term. 500° Term. 600° Term. 1000° Term. 1500° Term. 2000° Term. 3000° Term. 4000° Term. temp. temp. temp. temp. temp. temp. temp. temp. temp. temp. 654 4.6 981 69 1,308 9-2 1,635 115 1,962 13-08 3,270 230 4,905 345 6,540 460 9,810 690 13,080 92-0 2,518 17-7 3,777 26 5 5,036 35-4 6-295 44-2 7,554 531 12,590 88.5 66 On the Disguises of Nature: being an Inquiry into the Laws which regulate External Form and Colour in Plants and Animals. By ANDREW MURRAY, F.R.S.E.* I have long thought that an inquiry into the laws by which the external-or what may be called the extrinsic-forms and appearance of organic objects are regulated, might worthily and profitably exercise the faculties of some of our deeper thinkers. It is a subject to which, so far as I know, nothing has been done; at all events, no one has yet offered any explanation of what these laws are; and we may even be said to be ignorant whether there be any such laws or not. In the hope that a statement of the subject may induce some one better qualified than myself to turn his attention to it, I propose to group together a few facts illustrative of some of the different aspects in which the subject may be regarded, and to indicate the interesting nature of the speculations to which they may give rise. One very curious branch of the subject, with which I shall begin, is the resemblance which certain plants and animals bear to other objects, animate or inanimate, as, for instance, an insect to a leaf, a moth to a bee, &c. I have styled this the disguises of nature; a phrase which, although it does not apply to all the kinds of resemblance which I shall have to notice, sufficiently indicates their general nature. Other resemblances, such as the general family resemblance in the facies of animals spread over a whole continent, or the resemblance to be found in species confined to a particular kind of locality, will also receive a portion of our consideration; but these cannot be called disguises, and will fall to be discussed under a separate category. The disguise is usually one of two kinds. It is either an imitation of an animate or of an inanimate object. These we may take up separately. Not that I wish it to be thereby inferred that they differ from each other either in their conditions or the laws which regulate them; that is a question upon which we are not yet prepared to adjudicate; but I *Read before the British Association, Section D, September 1859. merely so take them for the convenience of obtaining some kind of order or arrangement into which to group the heterogeneous mass of facts which bear upon the subject. I shall first cast a hasty glance over a few of those curious resemblances where we find one animal assuming the form and appearance of another, as a butterfly pretending to be a wasp, a fly a bee, &c. I do not mean to include in this category those resemblances which the fancy of man loves to discover in all around him. Like Hamlet, we can see a camel or a weasel figured in every cloud, and, like his, they prove often very like a whale. It will be sufficient, as illustrations of such resemblances, to refer to the death's-head moth, which carries on its thorax not a bad figure of a death's head and cross bones; or to the Orchids and other Epiphytes, which we may compare to gaudy butterflies or other insects; or to the fern called Aspidium Barometz, known as the Tartarian or vegetable lamb. It grows on the elevated salt plains west of the Volga, and its rhizome presents, when the fronds are removed, a rude resemblance to the shape of the lamb. It is covered by a soft downy substance, of a reddish-brown colour, which may be compared to a fleece. Like the stems of other ferns, the inner parts are soft and pulpy, and the sap of a rich red colour resembling blood. From these materials a number of fabulous stories have been concocted, which are related by Struys and other authors such as that the plant has the shape and appearance of a lamb, with feet, head, and tail, distinctly formed; that it feeds upon grass, turning round upon its stem to reach it; that garments are made of its fleece; that the wolves feed upon it, and are very fond of its flesh, from the resemblance it bears in taste to the animal lamb; and, in conclusion, after telling a number of such tales, Struys adds with commendable, though somewhat tardy caution, "Many other things I was likewise told, which might however appear scarcely probable to such as have not seen them." But leaving such fancies, we shall find plenty of curious imitations among plants and animals, so exact, that man's fancy is not required to originate them, but his judgment to eliminate the deception. As we shall presently find in the other class of disguises, so here the greatest number is to be found in the insect tribes. The clear-wing moths have so great a resemblance to bees, or wasps, or flies, as to have received the name of Apiforme, Bombiforme, Vespiforme, Tipuliforme, according as they wear the dress of a honey-bee, a humble-bee, a wasp, or a gnat. Moths and butterflies, although belonging to very distinct divisions, sometimes assume the appearance of each other, as, for instance, Callimorpha helcita, and Danäe Hegesippe, which are so metamorphosed, that the moth might be taken for the butterfly, or the butterfly for the moth. Many moths also greatly resemble the Caddice flies (Trichoptera), as Adela frischella and Molanna angustata. A moth named Adactylus Bennettii, looks very like a small species of Tipula. Many two-winged flies have a most striking resemblance to bees, of which I may select, as examples, the Volucellæ generally, the Gasterophilus equi, or perfect insect of the Bot, and the Bombylii, more specially the Bombylius major, which carries its disguise farther than usual. Every one knows that the bee has a long tongue; the fly has not; but as if to imitate the long tongue of the bee, which is often extruded, the Bombylius has a long rostrum or snout sticking out like the tongue of the bee-the relative proportion being well preserved. The Asaphes, although bees, are yet bees of peculiar structure and habits: they make no hives or nests for themselves, but enter the nests of other bees, and deposit their eggs there, to be reared at the expense of the owners of the nest. They are dressed exactly like other species of Bombi, and doubtless thus escape detection on their pilfering and illegal expeditions. Psychoda phalenoides is a small two-winged fly, which anybody at first sight would mistake for a moth. Gibbium Scotias is a beetle, having considerable resemblance to a flea when seen in profile, and a still greater resemblance, when looked at from above, to a small brown spider, which every one sees too much of in summer. Many Coleopterous insects are found in ants' nests, seemingly created to pass their lives there; for some are eyeless, and many so exactly resemble the ants among which they live as to be not easily recognisable. Many examples of similarity between unlike and distant |