Sections of bone should also be made, both transverse and longitudinal.
The BLOOD is another object which must be carefully examined. The “corpuscles” which give the colouring matter to the blood are cells of different size, according to the creature from which they are taken. The dimensions of the animal exercise no apparent influence on the corpuscles, for those of “proteus anguinus,” a little creature not larger than a lamprey, are many times larger than those of the ox. In the accompanying [illustration] is shown a series of specimens, in order to show the great difference in their shape and size, all being drawn to scale and magnified by the same lens. The circular corpuscles in the left-hand upper corner are those of man; immediately below is a single corpuscle from the pigeon. The great central corpuscle is taken from the proteus; the two in the lower right-hand corner are from the frog, one of these being viewed edgeways; and of the remaining two, that on the left hand belongs to the tortoise, and that on the right to a fish.
BLOOD CORPUSCLES.
The insect tribes are an inexhaustible source of objects for the microscopist, who may find that even a single fly will give him employment for many months. The scales from the butterfly’s wing, the wonderful compound eyes with which insects are gifted, the structure of their feet, and their entire anatomy, are always at the service of any microscopist who really cares for his work. It would, of course, be impossible to give even a list of the interesting portions of the different insects; so one or two examples must suffice us.
ANTENNÆ OF FLY.
Take the ANTENNÆ of the insect tribes, and see how beautifully they are formed, how graceful is the shape, and how elaborate the structure. A low power will be useful for exhibiting their general shape and outline, but it is not until we know how to use the higher powers that the real beauty of these curious organs is seen. In the accompanying [illustration] is given part of an antenna of the common blue-bottle fly, in order to show the remarkable cavities which exist within the antennæ, and which are thought by some anatomists to be organs of hearing, and by others to be organs of smell.