536 BACTERIOLOGY. 



several times with the solvent to insure complete removal 

 of the paraffin. The washed sections can then be bottled 

 in 70 per cent, alcohol. 



The paramn should not be removed from the sections in 

 the manner described unless these are sufficiently thick to 

 hold together. Very thin sections are liable to fall to 

 pieces, and moreover, are difficult to handle in the sub- 

 sequent process of staining-. In such cases, it is advis- 

 able to fix the section to a cover-glass before removing 

 the paraffin. This can be easily done by the following- 

 method: 



The paraffin sections frequently become curled or folded. 

 This difficulty can be readily overcome by placing- the sec- 

 tions in some tepid water contained in a larg-e evaporating 

 dish. The water must not be so warm as to melt the paraf- 

 fin. The sections promptly spread out on the surface of 

 the water. They are now ready to be taken up on cover- 

 glasses. For this purpose only perfectly clean cover- 

 glasses (p. 140) should be used. 



A minute drop of the albumin fixative is placed on the 

 cover-glass and spread out in a very thin layer. The cover- 

 glass, thus prepared, and held in a pair of forceps, is placed 

 under the floating section. In this way the section can be 

 raised and removed from the water. The section should be 

 pressed out flat on the cover-glass by gently applying the 

 tip of the finger. The cover-glasses, thus equipped with 

 sections, are now set aside in the incubator at about 37 for 

 24 hours in order that the sections may become firmly fixed 

 to the glass. The paraffin can now be removed from the 

 cover-glass by treatment with toluol, or other . solvent, in 

 the manner indicated above. 



The albumin fixative is prepared by cutting- up the white of an 

 egg- with a pair of scissors. The liquid is then strained throug-h mus- 

 lin. An equal volume of glycerin is then added to the filtrate and 

 thoroughly mixed. A piece of camphor may be added to,prevent the 

 development of moulds. 



