226 Microscopical Examination of Tivo Minerals. 



the temporary contraction of sarcode, I have purposely avoided 

 drawing them. Moreover, in such a class of researches as the 

 present, where changes were almost momentary, it was only pos- 

 sible to draw from the best memory, as the lifting the eye from the 

 lens to make the drawmg on the spot would have been to forfeit the 

 more important information — the change which might take place 

 whilst engaged in the act of drawing. 



It has been chosen to draw attention to this subject of trans- 

 formation through the agency of Faramoecium for several reasons : 

 1st. It is a common subject of observation, and may be readily ob- 

 tained. 2nd. It is larger than Monas, and the changes are more 

 easily observed and less liable to mistake. 3rd. I have more 

 drawings of changes observed in this than any other infusorium. 

 Moreover, if the principle is allowed, one stage of transformation is 

 as good as another. 



It would, no doubt, have been more systematic to trace the 

 subject at once from Monas along the line up to Faramoecium ; but 

 here, until the principle is allowed, much difficulty would have 

 beset our inquiry, which is obviated by the use of Faramoecium to 

 endeavour to establish the rule. 



In observing on the unity of nature, which seems to be pointed 

 at by this and other facts especially noticeable, while making our 

 investigations on that debatable ground — the margin of Protozoa — 

 we are insensibly led to feel that the orb at least in which we dwell 

 is in an especial manner — 



" Totus teres atque rotundus." 



VI.— Microscopical Examination of Two Minerals. 



By Prof. A. M. Edwards. 



There was exhibited, at the last meeting of the Lyceum of Natural 

 History of New York, two specimens of minerals which, on account 

 of their peculiar characters, seeming to indicate that an examination 

 by means of the microscope would reveal facts of interest connected 

 with their source and origin, were referred to me for investigation 

 in that manner. I have viewed them by means of the microscope, 

 and now report upon them as follows : — 



The first is a specimen of marble reported to come from a spot 

 on the Adirondack and Lake George Eailroad, near Thurman 

 Station, Warren County, and about twenty-five miles from Saratoga 

 in this State, New York, and was pohshed so as to show its texture 

 very well. In colour it is white, mottled with light green, and 



