278 



LABORATORY GUIDE IN PHYSIOLOGY. 



4.. Precautions.- Care must be taken to have just the 

 proper amount of blood; too little will not spread well 

 and too much makes the spread too thick to examine 

 well. The blood should not have time to coagulate. The 

 cover glass should not touch the ear in obtaining the 

 blood. The blood can be made to flow again after it has 

 stopped by rubbing the ear briskly with a cloth. 



b. Fixing and staining. 



/. Appliances. Cover glasses; solution for staining; heater. 



2. Preparation. Clean cover glasses carefully with soap 

 and water, followed by alcohol. Instead of a copper 

 plate (Fig. 49) or oven over a Bunsen burner usually 

 used in laboratories, a heater as shown in Fig. 50 is rec- 



FIG. 49. 



FIG. 50. 

 FIG. 50. The water fixing plate. 



FIG. 49. Common copper heat- 

 ing plate. 



ommended. Cover glasses should be dried at boiling 

 point, which is constantly maintained in this heater, it 

 being filled with water and placed over a burner. There 

 is no danger of scorching, as there is on the strip of 

 copper over the Bunsen burner. With the pattern and 

 dimensions given in Fig. 51, any tinsmith can quickly 

 make the heater out of copper. 



(2) Prepare the following solution for staining: 



Ehrlich-Bondi powder (Griibler) 1 gm. 



One-half per cent sol. acid fuchsin 5 c c. 



Aqua dist 25 c.c. 



Let this solution stand one week and filter. 



