Remarks on Orgyia

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The President, Dr.



RUSCHENBERGER, in the chair.

Fourteen persons present. The death of J. B. McCreary, a member, was annouinced.





in the chair.

Sixteen persons present.

Explosion of a Diamond.-Prof. LEIDY exhibited a black agate sleeve button, having mounted upon it, centrally in a raised gold band, a rose diamond about 7 mm. broad. It had been submitted to him by Mr. Ernst Kretzmar, jeweller, who informed him that the person who wore it recently was leaning with his head upon his hand, on a window ledge in the sun, when the diamond exploded audibly, and witl. sufficient force to drive a fragment into his hand, and another into his forelhead. On examining the diamond, the fractured surface, following a cleavage plane, exhibits apparently the remains of a thin cavity, such as is sometimes seen in quartz crystals. The fracture also exposes a conspicuous particle of coal. Prof. Leidy thought that the explosion had been due to the studden expansion of a volatile liquid contained in the cavity, as frequently occurs in cavities in many minerals. Mr. Goldsmith thought that the liquid might be carbonic acid, as he was impressed with the idea that diamonds originated from this material in the liquid condition.



The President, Dr. RUSCHENBEROER,

in the chair.

Twenty-four persons present. The deaths of Francis Garden Smyth, M.D., a member, and Prof. Edouard Spach, a correspondent, were announced. LEIDY remarked that Orgyia leucosRemarks on Orgyia-Prof. tigma, which now seriously infested the shade trees of our city, especially the horse-chestnuts and silver-maples, had recently The trunks of the trees, and the passed into the moth stage. surrounding railing of the square opposite to the Academy ex-






hibit a profusion of cocoons. In seeking for specimens of the male motlh, he had collected only three, in a walk along one side of the square, firom the railing, where hundreds of the wingless females were to be olbtained, as they rested with their foamy white masses of eggs on their cocoons. From the fewniess of the males he was le(d to suspect that the females might, perhaps, in many To instances, (lel)osit the eggs in an unfecundated conidition. aseertaini if this were so, he collected several dozen cocoons with pup)e of females, distinguished by their comparatively robust clharacter, and placed them in a covered box in his study in the thiird stoiy of a back building, separated from the nearest place where tlhere were other cocoons by the front building and the widtlh of the street in front of hiis houise. As the females came ouit of the cocoons, distended with eggs, these, witlh the exception of a few wlhich appeared to he accidentally drlopped in several individuals, were retainied. After some days, as none of the females lai(d their eggs, the box was uncovered, and on the second morning subsequenitly, several individuials had deposited masses of eggs, thouglh no inales weie presenit in the box. However, on examining the vicinity, fouir male motlhs were detected on the outsi(de of tlhe curtain of the winidow in whiich thie box lhadlbeen placed, firom which it was supposed th'at the females lhad been visited by males attracte(d during the night from the neighborhood. The case related reminded him that some years ago a collector of buitterflies in the suburbs, iniformed him that he frequently obtained male specitnens of the Cecropia ancdLuna moths by pinning females to the side of the window, wheni, in the morning after, he would almost certainly finid males in conijunction with tlhem. The mean.s by wlicih the males thus find their mates at niglht and in out-of-the-way places were not obvious, as the insects appear to be incapable of producing sounds or scenits that are appreciable to our senses. J. M. Taylor was electe(d a member. Gustav Mayr, of Vienna, and C. Emery, of Palermo, were elected correspondents. AUGUST5. The President, Dr. RUSCHENBERGER, in the clhair. Sixteen persons present. AUGUST12. The Presidlent, Dr. RUSCHENBERGER, in the chair. Eighteen persons present.