LIST OF EBAGENTS, ETC. 393 



by the clips on tne stage. On or by the side of tbe 

 cover-glass is laid a small piece of paraffin, which melts 

 at the temperature at which the object is to be studied. 

 Let the tongue of the warm stage project into the flame 

 of an alcohol lamp. The tongue of metal will conduct 

 the heat back to the preparation on the slide, the tem- 

 perature of the latter being indicated by the condition of 

 the paraffin, which should be kept at the melting-point, 

 but not allowed to become fluid. If the stage become 

 too hot, cool it by removing the lamp for a time. 



44. Wicker sheimer^ s Fluid. 



Use. — Small animals — e. g., frogs — may be immersed in this 

 fluid for a week or two, then taken out and dried in the 

 air. Lungs, blood-vessels, and intestines should be filled 

 with the fluid, though this is not necessary in the case of 

 animals as small as the frog. The muscles, tendons, and 

 ligaments remain soft and flexible, and the natural color 

 of the organs is frequently well preserved. 

 Preparation. — In three thousand cubic centimetres of boil- 

 ing water dissolve one hundred grams of alum, twenty- 

 five grams of common salt, twelve grams of potassium 

 nitrate, sixty grams of potash, and ten grams of arsenic 

 trioxide. Cool and filter the mixture. Then to each ten 

 litres of the above mixture add four litres of glycerine 

 and one litre of ninety to ninety-five per cent, alcohol. 



