MOUNTING POLYZOA. 227 



ring; if it do, the whole must be rejected. Supposing 

 the precipitation to be complete, or nearly so, shake 

 vigorously for half an hour, and allow to stand till quite 

 cold ; the shaking must then Toe renewed, and the bottle 

 filled up with cold water. After allowing the precipitate 

 to settle for a day, draw off the clear supernatant fluid 

 with a syphon. Repeat the washing until the clear fluid 

 gives no precipitate with chloride of barium. So much 

 water must be left with the fluid that at last it may 

 measure 40 fluid ounces. For the injection-fluid, take 24 

 ounces of the above coloured fluid, and 3 ounces of good 

 gelatine; allow these to remain together all night, then 

 dissolve by the aid of a water-bath, and strain through 

 fine muslin. On injecting, the ordinary precautions for a 

 gelatine injection are alone necessary. 



Mounting Polyzoa. Mr. Morris, of Bath, has succeeded 

 in obtaining beautiful specimens of polyzoa and hydroid 

 zoophytes, with expanded tentacles, by adding spirit of 

 wine, drop by drop, to the salt-water cell in which they 

 have been confined. The polypidoms should be thus 

 treated as soon as possible after capture. 



A plan of mounting objects in a mixture of balsam and 

 chloroform is described by Mr. Win. Henry Heys in the 

 Microscopical Journal thus : Take a quantity of the oldest 

 balsam procurable, and place it in an open glass cup, and 

 mix with it as much chloroform as will make the whole 

 quite fluid, so that a very small quantity will drop from 

 the lip of the containing vessel. Then put this prepared 

 balsam into long thin half-ounce vials, and cork and set 

 them aside for at least a month. The advantage of having 

 it ready-made is, that there is no waste, and none of the 

 usual and troublesome preparation required for putting up 

 objects in Canada balsam; and if it has stood for some 

 time, it loses the yellow tinge which is observable in most 

 samples when first mixed, and, moreover, air-bubbles escape 

 more readily. 



Mr. Goadby's fluids are cheap and most effectual for 

 preserving and mounting animal structures in. The fol- 

 lowing are his formula : 



Take for No. 1 solution, bay salt, 4 oz. ; alum, 2 oz. ; 

 corrosive sublimate, 2 grains ; boiling water, 1 quart : mix. 



