Crosses Bxperiments loith the Voltaic Battery. 133 



batteries at work. One consisting of eleven pairs of cylinders, 

 made of four inch plates, between the poles of which is placed a 

 glass cylinder, filled with silicate of potassa, in which is suspended 

 a piece of slate between two wires of platina, as before, and cov- 

 .ered loosely with paper. Here, again, is another crop of insects 

 formed. The other battery consists of twenty pairs of cylinders, 

 the electric current of which is passed through six diiferent solu- 

 tions in glass cylinders, in three of which only is the insect form- 

 ed, viz. 1st, in nitrate of copper j 2d, in sulphate of copper, in 

 each of which the insect is only produced at the edge of the fluid, 

 as far as I can make out ; and 3d, by the old apparatus of coiled 

 silver and iron wire in silicate of potassa, as before. There are 

 now forming on the bottom of this positively electrified wire sim- 

 ilar insects, at the distance of fully two inches below the surface 

 of the fluid. On examining these, I have lately noticed a peculiar 

 quality they possess whilst in an incipient state. After being kept 

 some minutes out of the solution, they contract their filaments, so 

 as, in some cases, wholly, and in others partially, to disappear. 

 I at first thought they were destroyed ; but, on examining the 

 same spots, on the next day, they were as perceptible as before. 

 In this respect, they seem not unlike the zoophytes, which adhere 

 to the rocks on the sea-shore, and which contract on the approach 

 of a finger. I may likewise remark, that I have not been able 

 to detect their eyes, even when viewed under a powerful micro- 

 scope, although I once fancied I perceived them. The extreme 

 heat of summer and cold of winter do not appear favorable to their 

 production, v/hich succeeds best, I think, in spring and autumn. 

 As in the above account I have occasionally made use of the word 

 " formation," I beg that it might be understood that I do not mean 

 creation, or any thing approaching to it. I am not aware that I 

 have any thing more to add, except the few remarks I shall con- 

 clude with. 



1st. I have not observed a formation of the insect, except on a 

 moist and electrified surface, or under an electrified fluid. By 

 this I do not mean to assert that electricity has any tlnng to do 

 with their hirth, as I have not made a sufiicient number of exper- 

 iments to prove or disprove it ; and besides, I have not taken 

 those necessary precautions which present themselves even to an 

 unscientific view. These precautions are not so easy to observe 

 as may at first sight appear. It is, however, my intention to repeat 



