152 On Polarization of Light hy Living Animals. 



Roman dominion. Now it is exceedingly interesting to see 

 history and geology uniting for the purpose of solving ques- 

 tions relative to recent formations*. 



XXVII. On the Polarization of Light by Living Animals. 

 By J. F. GoDDARD, Lecturer on Optics, Sfc. at the Royal 

 Gallery of Practical Science. 



To the Editors of the Philosophical Magazine and Jour?ial 



of Science. 

 Gentlemen, 



/^N repeating the experiments published in 1816, and others 

 ^-^ subsequently noticed by Sir D. Brewster, on the polar- 

 izing property in the eyes of fishes and other animal sub- 

 stances, with my Polariscope, after observing that the scajf 

 sJcin of the human subject, sections of human teeth, ihefnger 

 nails, bones of fishes, &c. possessed the same property, I was 

 led to examine some living objects, when I discovered that, 

 among many others, the larvae and pupa of a tipulidan gnat 

 (the Corethra j)lti7nico)-7iis) possessed this property also, and 

 that in a very eminent degree. Its existence in the different 

 substances above enumerated is exceedingly interesting and 

 important ; but that it should also exist in living animals is 

 infinitely more so, and opens a new field altogether, disclo- 

 sing characters that lead to an intimate knowledge of their 

 anatomy, and which cannot possibly be discovered by any 

 other means. 



This creature is found in large clear ponds, generally in 

 great abundance when met with, but this is by no means 

 common. Having constructed a water trough, made with 

 two slips of glass about 1*25 inch wide and two inches long, 

 with very narrow slips of thin glass cemented with Canada 

 balsam between them, at the bottom and sides, thus leaving 

 it open at one end with about the 0*050 of an inch space be- 

 tween in the middle, I filled it with clear water in which I 

 placed some of the larvae; and such is the extraordinary 

 transparency of the creature, as to display in a most beautiful 

 manner the whole of their internal structure and organization, 

 and which, when viewed in polarized light, presents the 

 most splendid appearances. Thus when they place them- 



* The papers of this kind on the sestiiary of the Yare by Messrs. 

 J. W. Kobberds, and R. C. Taylor, Phil. Mag. & Annals, ^'.S. vols. i. ij. 

 1827, and those of Mr. Lyell, and Mr. Babbage, &c. have lately become 

 the sulyect of discussion in the Discorso of Sig. D. Paoli, " Del Solleva- 

 niento e del Avvallanicnto di alcuni Terreni :" Pesaro, 1838.— Ed. 



