384 THE AMERICAN MONTHLY [Dec. 



solution: Distilled water, 30 grams; sulphuric acid, 4 

 drops, (Schultze uses an acid, sp. gr. 1.839). At the end 

 of twenty-four hours' maceration it is sufficient to agitate 

 the lens in a drop of the liquid to obtain a great number 

 of perfectly isolated fibres. 



THE RETINA. 



/Sections of the Retina of the Crested Trito7i. — The whole 

 eye suspended from a cork, is exposed to the vapors of 

 osmic acid. In ten minutes transfer to the I alcohol, 

 and by a circular incision made with fine scissors, divide 

 into two segments. The posterior segment contains the 

 retina and is left in the alcohol for some hours. Transfer 

 to picro-carmine for a few hours. Thence transfer it to 

 two or three c. c. of osmic acid, 1 per cent. This reagent 

 fixes the easily changed elements of the retina. Wash 

 to free from the acid, and put in strong alcohol. In 

 twenty-four hours the hardening will be sufiicient to 

 allow of free-hand sectioning. These sections are beauti- 

 ful, but great skill is needed to make them. Imbed in 

 parafine, in which the elements are not sensibly altered, 

 aud mount' in glycerine or in balsam. 



Dissociation. — Place an eye of the crested triton in 1 

 per cent osmic acid. In twenty-four hours incise the 

 ball on a level with its equator, and place the posterior 

 segment in distilled water to macerate for two or three 

 days. Remove a fragment of the retina with curved 

 scissors, aad dissociate on a slide with needles. Picro- 

 carmine; glycerine. To macerate the retina fixed by 

 osmic acid we may use the -| alcohol, iodised serum or 

 very weak chromic acid. 



SECTIONS OF THE WHOLE EYE. 



It is sometimes necessary to make sections including 

 the organs of the eye in their respective positions. We 

 cannot dream of using a simple method, for it is abso- 



