MISCELLANEOUS COMMUNICATIONS. 165 



of these insects, when so able a one has been transmitted from Paris. It 

 seems they are of the genus acarus, but of a species not hitherto observed." 

 They have been seen and examined by many scientific men and eminent 

 physiologists, who all coincide with M. Turpin and the members of the 

 Academic des Sciences as to their genus and species. Mr. Crosse has never 

 ventured an opinion as to the cause of their birth. He conjectured that they 

 arose from ova deposited by insects floating in the air, and that they might 

 possibly be hatched by the electric action ; but he could not imagine that an 

 ovum could shoot out filaments, and that these filaments would become 

 bristles ; and he could not, on the closest examination, detect any remains of 

 a shell. Moreover, we have no right to assume that electric action is neces- 

 sary to vitality, until such fact shall have been most distinctly proved. Mr. 

 Crosse next imagined their origin from the water, and closely examined 

 several hundred vessels in the same room, filled with the same water as that 

 which held in solution the silicate of potassa , but could perceive no trace of 

 an insect of that description. He then examined the crevices and dusty 

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

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

 moistened birth-place, they issued out in different directions ; Mr. Crosse 

 supposed in quest of food ; but they generally huddled together under a 

 card or piece of paper in their neighbourhood, as if to avoid light or disturb- 

 ance. 



In the course of experiments upon other matters a glass basin was filled 

 with a concentrated solution of silicate of potassa without acid, in the middle 

 of which was placed a piece of brick, consisting chiefly of silica, connected at 

 each end with the poles of a voltaic battery of sixty -three pairs of plates, each 

 about two inches square. After many months' action, silica in a gelatinous 

 state formed on the bottom of the brick, and as the solution evaporated it was 

 replaced by additions, so that the outside of the glass basin being constantly 

 wet bv repeated overflowings was of course constantly electrified. On this 

 outside, as well as on the edge of the fluid within, the insects were similarly 

 produced. The apparatus was covered with them, they hid themselves 

 wherever they could find shelter, many were plainly perceptible to the naked 

 eye as they nimbly crawled from one spot to another. On examining the 

 table with a lens, no such excrescence as that which marks their incipient 

 state could be perceived. Other experiments were also in progress at this 

 time with different-sized batteries. On a clay slate suspended in a glass cy- 

 linder by two platina wires, in a similar solution to the foregoing, similar 

 excrescences and growth to perfect insects were observed. Between the 

 poles of one battery were interposed a series of seven glass cylinders, filled 

 with the following concentrated solutions :_1, Nitrate of copper; 2, subcar- 

 bonate of potassa ; 3, sulphate of copper ; 4, green sulphate of iron ; 5, sul- 

 phate of zinc; 6, water acidified with a minute portion of hydrochloric acid; 

 7, water poured on powdered metallic arsenic, resting on a copper cup con- 

 nected with the positive pole of the battery. All these cylinders were elec- 

 trically united together by arcs of sheet copper, so that the same electric cur- 

 rent passed through the whole of them. After many months' action, and 

 consequent formation of certain crystalline matters, similar excrescences 

 appeared at the edge of the fluid in every one of the cylinders excepting the 

 two whkh contained the carbonate of potassa and the metallic arsenic, and in 



