S62 THE AMERICA]^ MONTHLY [[Nov. 



pictures of the plexus and its connections with the brain may- 

 be obtained by killing in hot corrosive sublimate, staining for 

 twelve hours in Czokor's alum cochineal, and, dehydrating, 

 mounting in gum sandarac dissolved in absolute alcohol. 



In a second paper in the same journal, Dr. Wheeler also de- 

 scribes the method of studying the nervous system of Synchoe. 

 lidium. pellucidum. The brain and nerve trunks may be readily 

 seen in the living animal, but this is insufficient for study of 

 details. It is, however, only necessary to stain with alum coc- 

 hineal, extract as much of the stain as possible with water, 

 dehydrate and mount directly from absolute alcohol in gum 

 sandarac to obtain a diagram matically clear picture of all but 

 the very finest details of the nervous system. The nerves stand 

 out as white lines on a darker background. 



Preservation of Sea-"Weeds. — Dr. J. P. Dotsy recommends 

 the following method af preserving specimens of Floridea3, which 

 prevents swelling of the cell-walls or contraction of the proto- 

 plasm, and preserves the chromatophores uninjured. The speci- 

 men is first laid in a 1 per cent solution of chrome-alum in 

 sea-water, and kept there for a period varying from one to 

 twenty-four hours, according to the size and texture uf the 

 species. The chrome-alum is then completely washed out, and 

 the specimen placed in a mixture of 5 ccm. of 96 per cent alco- 

 hol in 100 ccm. water, and vigorously stirred. The amount of 

 alcohol is then increased by increments of 5 ccm. every quarter 

 of an hour until it amounts to 50 ccm. The specimen is then 

 removed, and placed in a mixture of 25 per cent alcohol in 

 distilled water, and the quantity of alcohol again increased in 

 the same way till it amounts to 50 ccm. alcohol to 100 ccm. of 

 water. The same process is again repeated with 50, 60, 70, 80, 

 and 90 per cent solutions of alcohol in distilled water, the spec- 

 imens being finally preserved in the last. 



Staining and Fixing Diatoms. — Dr. P. Miquel finds the 

 staining reagent best adapted for demonstrating the gelatinous 

 envelope of diatoms to be an aqueous or boric solution of 

 methylin-blue, which is not taken up so readily by the gelatin- 

 ous stipe. The same reagent, especially in a slightly ammoniacil 

 solution, may be used for demonstrating the nucleus, which is 

 stained blue, while other substances contained in the cell take 



