108 Manual of Veterinary Microbiology. 



pecially necessary in the examination of those tissues 

 for micro-organisms, as these latter, living independ- 

 ently, may continue to multiply after the death of 

 the tissues, and, further, in organs left in contact 

 with the air foreign germs generally develop which 

 are prejudicial to the accuracy of such researches. 

 These accidents are avoided hy immersing the tissues 

 to be preserved in absolute or, at least, strong alco- 

 hol, the precaution having been taken, in order to 

 render the action of the alcohol more rapid and more 

 intimate, to cut the organs into small cubes of half 

 to one centimeter on the side. 



Sectioning is performed in various ways, but the 

 technique of this operation can not be described 

 here ; its study belongs to the domain of histology. 

 Moreover, this mode of research does not appear to 

 be within reach of all practitioners on account of the 

 instruments and time which it requires, and, in 

 nearly all cases, it can be omitted when the differen- 

 tial diagnosis of infectious diseases is the only object 



in view. 



Mounting of preparations. 



Cover glasses. — After staining, the cover glasses 

 must be dehydrated to admit of their being mounted 

 in Canada balsam. This end is attained very rapidly 

 by drying them afresh over the flame of the spirit 

 lamp or upon the hot plate, after having previously 

 drained them between two folds of filter paper. As 

 soon as the cover glass is dried, the preparation is 

 cleared by depositing successively upon the coated 

 surface a drop of cedar oil, clove oil, or bergamot oil, 

 a drop of xylol, and, finally, a drop ot Canada bal- 

 sam dissolved in xylol. The cover glass is then 



