ON ACTIVE MOLECULES. 473 



often appearing to be flattened. Such oval particles were 

 found to be numerous and extremely active in white arsenig,. 



As mineral bodies which had been fused contained the 

 moving molecules as abundantly as those of alluvial de- 

 posits, 1 was desirous of ascertaining whether the mobility 

 of the particles existing in organic bodies was in any degree 

 affected by the application of intense heat to the containing 

 substance. With this view small portions of wood, both 

 living and dead, linen, paper, cotton, wool, silk, hair, and 

 muscular fibres, were exposed to the flame of a candle or 

 burned in platina forceps, heated by the blowpipe ; and in [u 

 all these bodies so heated, quenched in water, and imme- 

 diately submitted to examination, the molecules were found, 

 and in as evident motion as those obtained from the same 

 substances before biu-ning. 



In some of the vegetable bodies burned in this manner, 

 in addition to the simple molecules, primary combinations 

 of these were observed, consisting of fibrils having trans- 

 verse contractions, corresponding in number, as I conjec- 

 tured, with that of the molecules composing them ; and 

 those fibrils, when not consisting of a greater number than 

 four or five molecules, exhibited motion resembling in 

 kind and vivacity that of the mineral fibrils already de- 

 scribed, while longer fibrils of the same apparent diameter 

 were at rest. _ 



The substance found to yield these active fibrils in the 

 largest proportion and in the most vivid motion was the 

 mucous coat interposed between the skin and muscles of 

 the haddock, especially after coagulation by heat. 



The fine powder produced on the under surface of the 

 fronds of several Ferns, particularly of Acrostichum calo- 

 melanos, and the species nearly related to it, was found 

 to be entirely composed of simple molecules and their 

 primary fibre-like compounds, both of them being evidently 

 in motion. 



There are three points of great importance which I was 

 anxious to ascertain respecting these molecules, namely, 

 their form, whether they are of uniform size, and their 

 absolute magnitude. I am not, however, entirely satisfied 



