2116 Journal of Applied Microscopy 



A Method for Demonstrating Nematocyst Cells in Hydra. 



I. Slides prepared by the following method will be found helpful in demon- 

 strating to a beginning class in Zoology the number, position and distribution 

 of the stinging or Nematocyst cells of Hydra and others. 



Place a number of living Hydra in a Stender dish with a small amount of water. 

 The dish is placed in a good light and the Hydra allowed to become fully extended. 

 A volume of saturated solution of corrosive sublimate (HgCP) in 70 per cent, 

 alcohol equal to volume of water in Stender dish is heated boiling hot and 

 poured over Hydra. 



The Hydra are killed by this method with body and tentacles fully extended. 

 Wash in several changes of 70 per cent, alcohol, then pass successively through 

 50 per cent, alcohol, 35 per cent, alcohol, water, stain in an aqueous solution of 

 methylen blue for 5 minutes. 



Formula — 



Methylen blue - - , - 1 gram 



Castile soap .... .5 grams 



Water .... . 300 c. c. 



Pass hurriedly through following grades of alcohol, 35, 50, 70, 85, 90, 100 ; 

 clear in oil of cedar or bergamot and mount in balsam. 



The Nematocyst cells are stained a deep blue, all other cells are unstained, 

 exploded Nematocyst cells do not take the stain. 



This method has been found to give equally good results with Obelia, Gon- 

 ionemus and other ctelenterates. 



II. To stain living Hydra. 



Place Hydra in Stender dish with small amount of water ; with pipette place 

 two or three drops of the methylen blue solution directly on the specimen and 

 allow stain to act for from 5 to 10 minutes. The Hydra may then be placed in a 

 watch glass full of perfectly fresh water and examined under ;3 objective. 

 The Hydra will soon recover, the Nematocyst cells will be stained light blue, 

 while the other cells are the natural color. 



HI. If a large number of Hydra are desired for class use, the following 

 method will be found more satisfactory : 



Place the Hydra desired for use in a small vessel ; add enough of the methy- 

 len blue to the water in the vessel to make it sky blue. After about two hours 

 the Nematocyst cells of the Hydra will be stained, the Hydra may then be changed 

 to fresh water and are ready for class use. E. O. Little. 



DePauw University. 



To Remove Ftxed Stoppers, — Take the bottle in the left hand with the 

 forefinger applied to one side of the stopper, then tap the other side of the stop- 

 per with some heavy instrument, such as the handle of a pocket-knife, pressing 

 the forefinger against the direction of the tap. Turn the bottle round, gradually 

 tapping until the stopper loosens. Should this device prove of no avail (which 

 is very rarely), hold the neck of the bottle in a spirit fiame. and quickly with- 

 draw the stopper as the glass of the neck expands. This is a somewhat risky 

 procedure, but is very effectual if done smartly. 



