272 ANNUAL OF SCIENTIFIC DISCOVERY. 



fermentation to set in ; while the same experiment with the highly 

 crystalline varieties of carbonate of lime produces no trace of 

 such a phenomenon. 



PLATEAU ON THE FLIGHT OF COLEOPTERA. 



M. Felix Plateau has supplemented the recent labors of Marey 

 and others upon the flight of insects by examining the movements 

 of the wings of certain Coleoptera. Specimens of the common 

 May-beetle and Oryctes nasicornis were selected for experiment. 

 The apparatus used consisted of 2 pulleys, fastened one above 

 the other, at a distance of 2 centimetres, on a vertical support ; the 

 upper pulley made 12 turns for each one made by the lower, and 

 could be caused to rotate 24 times in a second. The insects were 

 killed by ether vapor immediately before each experiment ; and 

 the wings could be fastened, by a simple contrivance, to the front 

 prolongation of the axis of the upper pulley. A wing, in its folded 

 state, was fixed on the instrument in such a manner that its plane 

 made with the plane of rotation an angle of 45, as in the living 

 animal. On turning the pulleys, it struck the air obliquely by its 

 upper surface and front margin ; but the small diameter of the 

 apparently continuous revolving disc (as indicated by a graduated 

 scale) proved that the wing was still folded, and that centrifugal 

 force had not affected it. When rotation was produced in an 

 opposite direction, so that the wing struck the air both by its pos- 

 terior membranous margin and inferior surface, the increasing 

 diameter of the disc gave proof of the expansion of the wing, 

 which, indeed, continued to be much extended when motion was 

 arrested. When the plane of a wing was perpendicular to the 

 plane of rotation, and the revolution of the wheel was such that 

 the wing struck the air by its dorsal or upper surface, no exten- 

 sion ensued ; when it struck by its lower surface only partial ex 

 tension followed. Now the oblique, not the perpendicular, plane 

 is that chosen by nature, and is, as has been seen, much more 

 favorable for flight. On fixing an open wing on the axis so as to 

 make an angle with the plane of rotation, and turning in one 

 direction, the wing remained open ; on reversing the direction 

 (that is, acting on the upper surface), it became partially closed. 

 Nature. 



HEAT EVOLVED BY INVERTEBRATE ANIMALS, ESPECIALLY 



INSECTS. 



In the "Annales cles Science Naturelles," tome xi. (18G9), 

 p. 184; "Bibl. Univ.," January 15, 1870; " Bull. Sei.," p. 83, can 

 be found memoirs on the above subject. 



Mr. Giraud's researches have been made by various processes. 

 He has employed the mercurial thermometer, the little bulb of 

 which he has succeeded in introducing into the rectum of cater- 

 pillars and other insects without injury to the animal. ^ He has 

 also made use of the differential thermometer of Leslie, in which 



