Crosse's Expermients ivith the Voltaic Batteiy. 129 



these little mites, when so excellent a one has been transmitted 

 from Paris. It seems that they are of the genus Acarus, but of 

 a species not hitherto observed. I have had three separate forma- 

 tions of similar insects at different times, from fresh portions of 

 the same fluid, with the same apparatus. As I considered the 

 result of this experiment rather extraordinary, I made some of 

 my friends acquainted with it, amongst whom were some highly 

 scientific gentlemen, and they plainly perceived the insect in va- 

 rious states. I likewise transmitted some of them to one of our 

 most distinguished physiologists in London, and the opinion of 

 this gentleman, as well as of other eminent persons to whom he 

 showed them, coincided with that of the gentlemen of the Acade- 

 mic des Sciences, as to their genus and species. / have never 

 ventured an opinion as to the cause of their birth, and for a very 

 good reason— I was unable to form one. The most simple solu- 

 tion of the problem which occurred to me, was, that they arose 

 from ova deposited by insects floating in the atmospherCj and that 

 they might possibly be hatched by the electric action. Still, I 

 could not imagine that an ovum could shoot out filaments, and 

 that those filaments would become bristles ; and moreover, I 

 could not detect, on the closest examination, any remains of a 

 shell. Again, we have no right to assume that electric action is 

 necessary to vitality, until such fact shall have been most dis- 

 tinctly proved, I next imagined, as others have done, that they 

 might have originated from the water, and consequently made a 

 close examination of several hundred vessels, filled with the same 

 water as that which held in solution the silicate of potassa, in 

 the same room, which vessels constituted the cells of a large Vol- 

 taic battery, used without acid. In none of these vessels could 

 I perceive the trace of an insect of that description. I likewise 

 closely examined the crevices and most dusty parts of the room 

 with no better success. In the course of some months, indeed, 

 these insects so increased, that when they were strong enough to 

 leave their moistened birth-place, they issued out in different di- 

 rections, I suppose, in quest of food ; but they generally huddled 

 together under a card or piece of paper in their neighborhood, as 

 if to avoid light and disturbance. In the course of my experi- 

 ments upon other matters, I filled a glass basin with a concentra- 

 ted solution of silicate of potassa without acid, in the middle of 

 which I placed a piece of brick, used in this neighborhood for 

 Vol. XXXV.— No. 1. 17 



