148 Motion of Particles on Melted Spermaceti. 



the former, after a number of days, (six or eight,) was as much a 

 flirt as ever, wriggling and flouncing at every touch. 



December 12, 1840. — In a former letter, I contrasted the vi- 

 tal tenacity of a Lepidium, with that of a common fly. The 

 Lepidium is still alive. It has been kept since the date of that 

 letter as it had been before, in a perfectly clean cupping glass, 

 covered with another cupping glass, so that to human perception, 

 life has been sustained without subsistence for many months. 

 The continuance of the insect's existence is in no degree due to a 

 state of torpidity during this cold weather. 



In the summer, the larvae of the lady-bug, (slate-colored wings 

 with sixteen black dots, the two near the neck approximate,) were 

 very numerous about my residence, and attached themselves, af- 

 ter their aphidivorous career, to the trees, walls and other neigh- 

 boring objects, by their posterior extremity. The little birds stole 

 away many of them ; but others were well ensconced, and they 

 fell to my share. Thus adherent, the larvae struggle by occasion- 

 al jerks, for several days, to disengage themselves from their en- 

 velope. At last a buff-colored, elliptical and rugose thing appears, 

 the old integument having been slipped down into a dense mass ; 

 and in twelve hours, the black spots appear upon its partially de- 

 veloped wings. It remains firmly fastened to its original point for 

 a day or two longer, when another integument is thrown off" as 

 before, and the perfect bug walks forth. It does not immediately 

 leave the spot ; but remains a long time in the vicinity of its exu- 

 viae, perambulating around them as if exulting at its escape from 

 so mean a habitation. These larvae are covered with spines. In 

 several instances, those that were so unfortunate as to have attach- 

 ed themselves early, were attacked by those still at liberty, and 

 destroyed : the prisoner showed by his contortions, &c., that he 

 suff"ered from the wound. I saw one of the semi-developed bugs 

 destroyed in the same manner; and one of \k\Q perfect bugs prey- 

 ing upon an attached larva. Thus voracity continues through 

 all the stages of its metamorphosis : the larva living upon its own 

 grade, and the winged bug, upon the larvae. 



Motion of Particles on Melted Spermaceti. — In relation to some 

 remarks in a former number of this Journal, Vol. xxxiii, p. 198, on 

 a singular phenomenon in a burning candle, in which a particle 

 floating upon the melted spermaceti, alternately approached to 



