34 HISTORY OF BRITISH ZOOPHYTES. 



gratify some ladies who were fond of natural science, I put 

 a little iodine into a small pliial, and having corked it, I 

 thought, before giving it to the ladies, that I would try 

 whether it answered my expectations ; so, holding it in the 

 flame of the fire, I soon had the pleasure of seeing the 

 little bottle filled with the violet"^ fumes. The vapour dis- 

 appeared so soon as the phial cooled. This I expected : 

 but obser\ing that there was a deposit on the glass inside, 

 I applied a pretty powerful pocket-lens to it, and was de- 

 lighted to find that the deposit which dimmed the glass 

 consisted of beautiful dendritic crystallizations very much 

 resembling those moss-like figures which I had admired on 

 the Irish limestone. This is an experiment which, with the 

 same enclosed particles of iodine, may be repeated as often 

 as you choose ; and on every repetition there will be a new 

 set and arrangement of figures, like the numberless changes 

 that take place on shaking a kaleidoscope. 



"When theories are plausible, they often keep their ground 

 for a considerable time in the minds of many, even after 

 accurate observers have become acquainted with the truth, 

 and have ventured to pubHsh it. The light of truth on 

 this subject began to dawn about the close of the sixteenth 



* lodiue takes its name from the Greek word for a violet. 



