MAKING COVER-GLASS PREPARATIONS 25 
Cover-glass preparations of bacteria are permanently mounted 
. the same manner as similar preparations made from the 
ood or other tissues in histology, the process being to put a 
‘op of balsam on the center of the slide and place the prep- 
ation, film downward, over it and apply slight pressure. 
abel the preparation, giving the name of the organism, its 
vurce (kind of culture, tissue, etc., from which the preparation 
as made), stain used, and date. If the specimen is not pre- 
ved, the slide and cover glass should be cleaned for future use. 
35. Suggestions concerning the microscopic examination of 
ined preparations of bacteria. In the examination of the 
acteria in the stained condition the following points, and 
athaps others, should be observed and noted. (a) Concern- 
iy their morphology. Are they spherical, rod-shaped, or 
viral? Are they separated or united in clumps or chains? If 
id-shaped, are the ends pointed, round, or square? Are the 
acteria all of the same form and size? Note the presence 
: absence of spores, granules, and capsules. (6) Concerning 
‘eir reaction to staining fluids. Do they stain uniformly or 
regularly? Do they stain deeply or faintly? Is the center 
zhter than the periphery? Are there an unstained central 
ind and deeply stained ends (polar stain)? Do all of the 
icteria take the stain alike? 
36. Staining solutions. The basic aniline dyes are used in 
aining bacteria. There is a large number of these, and there 
‘e several formule for preparing staining solutions from 
ich. Further, as will be seen from the chapters on staining 
icteria in the text-books, there are several methods of apply- 
g these stains. In an introductory course, however, it is 
rpossible to try them all, and consequently only those are 
ascribed which seem to be the best adapted for general use. 
In addition to the ordinary staining solutions and methods 
ere are special processes for certain species, such, for exam- 
e, as the tubercle bacterium, and still others for staining 
‘tain parts of many bacteria, such as the flagella on motile 
