1896 THE MICROSCOPE. 123 



Chlorinated lime twelve troy ounces, water twelve 

 pints. 



Dissolve the carbonate of soda in three pints of water, 

 with the aid of heat. Triturate the chlorinated lime, a 

 little at a time, with small portions of the water, g-radually 

 add until a smooth uniform mixture is obtained. Mix this 

 intimately with the remainder of the water, and set the 

 mixture aside for twenty-four hours. 



Then decant the clear liquid, and, having- transferred 

 the residue to a muslin strainer, allow it to drain until 

 sufficient liquid has passed to make, with the decanted 

 liquid, eig-ht pints. Mix the liquid thoroug-hly with the 

 solution of carbonate of soda, transfer the mixture to a 

 muslin strainer, and allow it to drain, adding- water if nec- 

 essary toward the close, until eleven pints and a half of 

 the liquid have passed. Lastly put in bottles well stopped, 

 with glass stoppers, in a cool dark place. 



Mounting Hydra. — Fresh specimens are infinitely more 

 interesting than any mounted one can possibly be, but 

 they may be mounted. To mount them place in a cell 

 filled with water and cover. Watch when the tentacles are 

 expanded ; at this moment hold the slide over and close to 

 the chimney of a student lamp. This latter process will 

 kill the animal and prevent the retraction of the tentacles. 

 Then remove the water from the cell with a blotter and 

 fill the cell with a solution of chloral hydrate. The mount 

 may then be sealed and the animal preserved indefinitely. 



It is said that an osmic acid solution will kill the animal 

 without retraction or shrinking. 



Carpenter recommends a mixture of nine parts of a one 

 fourth solution of chromic acid with one part of a one per 

 cent solution of osmic acid and says that after being sub- 

 jected to the agent the specimen should be treated with 

 fifty per cent alcohol gradually increased in strength to 

 absolute. This latter ag-ent is said to be applicable for 

 fixing and preserving infusoria, rotifera, desmidicae, dia- 

 tomacae, bacteria and other delicate veg-etable and animal 

 structures. 



