1. Transpiration through the Slifer's patches of the desert locust (Schistocerca gregaria) was demonstrated experimentally, and was found to be greater than that through the normal cuticle at room temperature (20° C). The difference increases at higher temperatures. Similar results were obtained with other acridids. Death of the animal appeared to have no effect on the phenomenon.

2. Tentative estimations of the patch transpiration rate gave very high values, probably exaggerated by pinhole diffusion. The surprising figure of 169±52mg./cm.2/hr. at about 45° C. was obtained with living preparations. With dead ones and a different method, the values were smaller, being near-zero below 40°C but increasing fairly steeply from 45° to 60° C.

3. It is suggested that the patches might show a transition effect at 40° C. Some superficial lipid which appears to melt at 45° C. all over the cuticle may be connected with the high permeability of the patches.

4. The structural peculiarities of the patches can be explained as adaptations to a high transpiration rate. The patches may form an emergency cooling system, but other functions are not excluded.

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