Jak. 1, 1865.] 



SCIENCE-GOSSIP. 



21 



stir out of our rooms. Tlie very liairs on our head 

 may be made objects of interesting investigation ; 

 and especially if we compare them with, the hairs of 

 otlier animals, and the appendages generally of the 

 skin. The fine outer coating of the skin is composed 

 of minute scales, which ai'e flattened cells, and may 

 be easily observed by scraping a portion of the skin 

 on to a glass slide, v.'ith a di-op of water on it. The 

 nails, the hairs, and other appendages of tbe skin, 

 are composed of the same kind of scales or cells. 

 These cells are developed in little pits, or follicles, 

 from wMch the hair is projected, as it were, by their 

 growth from below. Under a low power the cells of 

 tbe human hair cannot be observed. It presents, how- 

 ever, a well-marked distinction between the outside, 

 or cortical layer, and the interior, or pulp. The 

 latter, by a high powei", especially if the hair has 

 been first submitted to the action of sulphuric acid, 

 will be found to contain cells more or less spherical, 

 whilst the former contains cells more or less flattened. 

 These project a little beyond the edge of the hair, so 

 that its sides are not quite smooth. By placing 

 a hair between two pieces of cork, fine transverse 

 sections of it may be made by means of a sharp 

 razor. If these are put under the microscope, 

 the pulpy portions will present a dark appear- 

 ance in the centre. The hairs of animals ofler a 

 great variety in the disposition of the cells of which 

 they are composed. The hairs of the mouse present 

 a series of dark partitions running across the hair 

 between the cells. In the younger hairs, these 

 partitions are single, whilst in the older ones they 

 appear double. The hairs from the ear of the mouse 

 present these dark partitions very distinctly. Such 

 hairs stand intermediate between true hair and 

 wool. A piece of flannel, or blanket, will afford a 

 good illustration of the latter. In this case it will 

 be seen that the scales, or cells, of the cortical part, 

 project beyond the surface, and render the wool 

 rough. This roughness of the outside is supposed 

 to render such hairs fitted to be used in the process 

 of felting; the rough sides of the hairs adhering 

 together. The chemical composition of the hair has 

 also something to do with this process. Human, 

 and other smootli hairs, will not felt. — Br. La>i/cesler's 

 Half-hours with the Microscope. 



The Scales op Insects.— -The fine dust upon 

 the wings of moths and butterthes, which is so 

 readily removed when handled carelessly, is what is 

 generally called scales. To these the wing owes the 

 magnificent colours which so often are seen upon it; 

 every particle being what may be termed a distinct 

 flat feather. How these are placed (somewhat like 

 tiles upon a roof) may be easily seen in the wing of 

 any butterfly, a few being removed to aid the inves- 

 tigation. The form of them is usually that of the 

 '•'battledore" with which the common game is 



played, but the handle or base of the scale is often 

 short, and the broad part varies in proportionate 

 length and breadth m different specimens. The 

 markings upon these also vary, some being mostly 

 composed of lines running from the base to the 

 apex, others reminding us of network — bead-like 

 spots only are seen in some — indeed, almost endless 

 changes are found amongst them. These scales are 

 not conflned to butterflies and moths, nor indeed to 

 the icings of insects. The different gnats supply 

 some most beautiful specimens, not only from the 

 wings, but also from the proboscis, &c. ; whilst from 

 still more minute insects, as the podura, scales are 

 taken which were at one time esteemed as a most 

 delicate test. Tiie gorgeous colours which the 

 diamond beetles also show when under the micro- 

 scope are produced by light reflected from minute 

 scales with which the insects are covered. 



In mounting these objects for the microscope it is 

 well to have the part of the insect from which the 

 scales are usually taken as a separate slide, so that 

 the natural arrangement of them may be seen. 

 This is easily accomplished with the wings of but- 

 terflies, gnats, &c., as they require no extraordinary 

 care. In mounting the scales they may be placed 

 upon slides, by passing the wings over the surface 

 or by gently scraping the wing upon the slide, when 

 they must be covered with the thin glass. Of course, 

 the extreme tenuity of these objects does away with 

 the necessity of any cell excepting that formed by 

 the gold-size or other cement used to attach the 

 cover. The scales of the podura should be placed 

 upon the slide in a somewhat different manner. 

 This insect is without wings, and is no longer than 

 the common flea. It is often found amongst tlie 

 sawdust in wine-cellars, continually leaping about 

 by the aid of its tail, which is bent underneath its 

 body. Dr. Carpenter says : — " Podurse may be ob- 

 tained by sprinkling a little oatmeal on a piece of 

 black paper near their haunts : and after leaving it 

 there for a few hours, removing it carefully to a large 

 glazed basin, so that, when tliey leap from the paper 

 (as they will when brought to the light), they may 

 fall into the basin, and may thus separate themselves 

 from the meal. The best way of obtaining their 

 scales is to confine several of them together beneath 

 a wine-glass mverted upon a piece of fine smooth 

 paper ; for the scales will become detached by their 

 leaps against the glass, and will fall upon the paper." 

 These scales are removed to the slide, and moimted 

 as those from the gnats, &c. When the podura has 

 been caught without the aid of the meal, it may be 

 placed upon the slide, under a test-tube, or by any 

 other mode of confinement, and thus save the trouble 

 of transfer from tbe paper before mentioned. An- 

 other method is to seize the insect by the leg with 

 the forceps and drag it across the slide, when a suf- 

 ficient quantity of scales will probably be left nprr. 



