118 



STAINING OF BACTERIA 



and floating them in warm water (about 35 to 40 C.), when they 

 flatten out perfectly. The next step is to prepare a clean slide by 

 rubbing over it a small amount of egg-albumen mixture composed of 

 equal parts of beaten white of egg and glycerin, which has been 

 filtered. This egg-albumen glycerin mixture will fix the section on 

 the slide. Dip the slide into the warm water where the section is 

 floating, and guide the latter with a platinum rod or tissue needle 

 onto the slide and move to the part previously prepared with the 

 egg-albumen. After the section is in position the slide is placed for 

 several hours in the incubator to evaporate the water. The section 

 now rests perfectly flat on the dry slide. 



FIG. 54 



Paraffin -embedding oven. 



Removal of Paraffin. It is now necessary to fix the section and 

 remove the paraffin. This is done in the following manner. 



1. Move the slide over a flame (alcohol lamp or small flame of 

 Bunsen burner) until the paraffin melts. Then heat a little longer, 

 so that the egg-albumen coagulates and fixes the section on the slide. 

 This manipulation requires some experience which can be gained 

 only by practice. If heated too much the section will be more or 

 less damaged, and if heated too little there is great danger of the 



