Abstract
It has long been known that blood or hemolymph circulates in the wings of certain insects (Carus, Moseley, Brocher, and others). Most of these authors apparently observed the wing circulation with difficulty and were unable to identify completely the circulation scheme in a single insect wing at a given time. Such circulation diagrams, therefore, represent averages of a number of observations and conjectures based upon these. Brocher, 1 until recently, 2 saw the movement of individual blood cells only occasionally. Moseley 3 was unable to observe blood circulation in the forewing of the cockroach, P. orientalis.
The present paper reports a simple method of observing the details of blood circulation in the wings and wing-pads, as well as in the appendages and certain portions of the body, of the cockroach, P. americana.
Circulation in the forewing may be observed by placing the animal in a depression made in a piece of balsa wood; the depression should just fit the insect and should be of such depth as to leave the dorsal surface of the body slightly higher than the surrounding wood. The head and pronotum are retained by a piece of paper (Fig. 1, p) pinned to the wood (w); the abdomen and all but the forewing (F) to be observed are held in a similar manner by a piece of dull black paper (b). The wing (F) should be at an angle to the black paper (b), upon which is placed a movable piece of white kymograph paper (k) with the shiny surface uppermost, so that a beam of intense light (l) from a low voltage incandescent lamp (L) can be directed downward to the edge (e) of the kymograph paper, as shown by the arrow in Fig. 1.
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