Figs. [35] and 36 are the small and large hairs of that magnificent creature, the sea mouse (Aphrodíte aculeáta), whose covering, although it lies in the mud, glows with every hue of the rainbow, and in a brilliant light is almost painfully dazzling to the eye.
VIII.
| FIG. | |||
| 1. | Boat-fly, leg | 23. | Do. Human Beard |
| 2. | Gadfly, empty egg | 24. | Do. do. aged |
| 3. | Diamond Beetle, scale | 25. | Do. Humble Bee |
| 4. | Scale, Fritillary, Adippe | 26. | Do. Tiger Moth, Larva |
| 5. | Egg, Tortoiseshell Butterfly | 27. | Do. Dormouse |
| 6. | Head and Eyes, Zebra Spider | 28. | Do. Rat |
| 7. | Eyes, Bed-Bug | 29. | Do. do. long hair |
| 8. | Scale, Death’s-Head Moth | 30. | Do. Sheep |
| 9. | Sting, Wasp | 31. | Do. Mole |
| 10. | Scale, battledore, Azure blue | 32. | Do. Rabbit |
| 11. | Do. ordinary scale | 33. | Scale, Greenbone Pike |
| 12. | Eye, Harvest Spider | 34. | Hair, Red Deer |
| 13. | Wing Membrane, Azure Blue | 35. | Do. fine, Sea Mouse |
| 14. | Scale, Anthocera cardaminis | 36. | Do. do. large |
| 15. | Do. Peacock Butterfly | 37. | Do. do. Badger |
| 16. | Do. Tiger Moth | 38. | Do. do. long-eared Bat |
| 17. | Do. Thigh of Tiger Moth | 39. | Fibre, Linen |
| 18. | Wing and Scales, Azure Blue | 40. | Do. Cotton |
| 19. | Scale, Lepisma | 41. | Do. Silk |
| 20. | Saws, Sawfly | 42. | Scale, Perch |
| 21. | Scale, Podura | 43. | Do. do. |
| 22. | Hair, Black Human |
VIII.
The scales of some of the fishes are shown on Plate [VIII]., in order to exhibit their mode of growth by successive layers. The scales are always enveloped in membranous sacs, and in some cases, as in the eel, they do not project beyond the surface, and require some little observation to detect them. A scale of an eel is shown on Plate XI. Fig. [14], and is a magnificent object under polarised light. Fig. [33] is a scale of the greenbone pike; and Figs. [42] and 43 are scales of the perch, showing the roots by which they are held in their places. The roach, dace, bleak, and many other similar fish have a beautiful silvery substance on the under surface of the scales, which was greatly used in the manufacture of artificial pearls, glass beads being thinly coated in the interior with the glittering substance, and then filled in with wax. A piece of sole-skin, when preserved in Canada balsam and placed under the microscope, is a very beautiful object.
More examples of hairs, and other processes from the skin, together with the structure of the skin itself, of bone, of blood, and the mode in which it circulates, are given on Plate [X].
In all important points of their structure the feathers of birds are similar to the hairs of animals, and are developed in a similar manner. They are all composed of a quill portion, in which the pith is contained, and of a shaft, which carries the vane, together with its barbs. The form of each of these portions varies much, even in different parts of the same bird, and the same feather has almost always two kinds of barbs; one close and firm, and the other loose, floating, and downy. If a small feather be plucked from the breast or back of a sparrow or any other small bird, the upper part of the feather is seen to be close and firm, while the lower is loose and downy, the upper part being evidently intended to lie closely on the body and keep out the wet, while the lower portion affords a soft and warm protection to the skin.
Fig. [12], Plate X., shows the feather of a peacock, wherein the barbs are very slightly fringed and lie quite loosely side by side. Fig. [18] is part of the same structure, in a duck’s feather, wherein are seen the curious hooks which enable each vane to take a firm hold of its neighbour, the whole feather being thus rendered firm, compact, and capable of repelling water. The reader will not fail to notice the remarkable analogy between these hooks and those which connect the wings of the bee.