106 Manual of Veterinary Microbiology. 



in succession, the various manipulations to which the 

 liquids, pulp, and sections of organs must be sub- 

 jected. 



Liquids — Direct examination. — A drop of the liquid 

 is deposited upon a slide, covered with a cover glass, 

 and at the margin of the latter is placed a drop of 

 coloring matter ; penetration gradually takes place, a 

 process which may be assisted by manipulation of 

 the cover glass. We may also add a trace of coloring 

 matter directly to the drop of liquid to be examined 

 before inclosing it under the cover glass. For this 

 purpose aqueous solutions of gentian violet or methyl 

 violet are generally employed. 



Examination after desiccation. — The preparation just 

 described has its field of usefulness, but it has the de- 

 fect of not being permanent, and, especially, of not 

 permitting of double staining. To attain these ends 

 the liquids are rapidly dried so as to fix the elements 

 w^hich they contain and cause them to adhere to the 

 glass. In this process a drop of liquid is spread on 

 a cover glass either by means of a spatula or by 

 pressing the drop betw^een two cover glasses which 

 are glided upon each other and then separated. The 

 cover glasses, thus coated, are held over the flame of 

 a spirit lamp or placed upon a hot plate, the surface 

 containing the liquid to be examined being directed 

 upward so as not to be attacked by the flame. The 

 drying is suflicient when the liquid is transformed 

 into an opalescent layer ; tins layer then intimately 

 adheres to the cover glass, which can be then trans- 

 ported through a series of reagents without risk of 

 the former becoming detached. 



The quantity of liquid employed should be very 



