238 Miscellaneous. 



buried in the sand, so that in order to escape it has to make its way 

 through the new-formed stratum of sand, it forms a deep and narrow 

 hole. If the air, instead of escaping at once, bubbles up several times, 

 then it raises around the hole a small and smooth rim, which may be 

 compared to a miniature crater of a volcano. If, on the contrarj*, the 

 air-bubble remains at the surface and bursts, then it causes a flat 

 and rather large impression. According to Messrs. Whitney and 

 Desor, these diiferent fonns of impression arising from air-bubbles 

 are sufficient to account for most impressions which have hitherto 

 been considered as the effect of rain. Such impressions of air-bubbles 

 are most perfect where the slope of the beach is very gentle. Where 

 the slope is more or less steep, the sand becomes too much hardened 

 under the pressure of the waves to allow these delicate impressions to 

 be produced. 



A sketch was exhibited, showing these different forms of impressions, 

 and their striking contrast with impressions of rain drops from the 

 same beach, mouth of Carp River, Lake Superior. 



Mr. Teschemacher said, that he had seen fossil rain drops, so-called, 

 with an elevated ridge crossing them ; an appearance easily explained 

 by Mr. Desor' s hypothesis, but incompatible with the supposition that 

 they were caused by rain. 



Prof. Agassiz said, that on the mud flats at Cambridge, he had 

 noticed impressions made in the way described by Mr. Desor at Lake 

 Superior.— Proc. Bost. Soc. Nat. Hist. 1850. p. 200. 



On the Occurrence of Crystalline Bodies in Animal Tissues. 



Dr. Leidy remarked that crystalline bodies had been detected in 

 most of the tissues of many plants, but that their occurrence in 

 animal tissues was much more rare. The deposit of earthy salts in 

 many tissues, such as bone, enamel and shell, though analogous, was 

 not homologous with crv'stallization. The earthy deposit in the shell 

 of the egg of many animals is probably an instance of true crystalliza- 

 tion within an animal tissue, for in those animals which have eggs with 

 a semi-membranous shell, as many helices, &c., we can detect the car- 

 bonate of lime deposited in the form of regular rhombohedrons. He 

 stated that he lately met vrith a remarkable instance of ciystallization 

 within animal organic cells. In examining the stomach of the larva of 

 Arctia Isabella, a Lepidopterous insect, he found that the micleus of 

 every epithelial cell contained an octohedral crystal, the axes of which 

 measured about the l-3750th of an inch. The cells were colourless, 

 (not white,) containing some faintly granular matter, which in many 

 instances was collected into distinct rounded masses. The nuclei 

 were round, elliptical, or lenticular, transparent, and measured the 

 1-1 666th of an inch when round. The following day, upon exami- 

 ning some of the cells, which had been preserved between two sUps of 

 glass hermetically sealed, the crystals had disappeared, and the nuclei 

 had become distinctly and opakely granular. Acetic acid rendered 

 the granular matter more translucent, and brought into laew the 

 nucleolus, which, not being visible the preceding day, probably served 

 as the nucleus of the crystalline body. The animal, when examined, 

 was in a state of hybernation, at which period organic activity is 



