72 MOUNTING AND PREPARATION OF OBJECTS. 



bubbles are under the cover glass ; it is allowed to 

 remain twenty minutes. It is then placed in the 

 acid solution, number 3, until the colour is removed, 

 for about ten minutes. It is then washed in distilled 

 water until the nitric acid is removed, and then 

 placed in a little chrysoidin solution which has been 

 filtered into a watch glass, for a few minutes. It 

 must again be washed in distilled water, and the 

 superfluous water drained off on filtering paper ; it 

 is then placed in absolute alcohol and dried tho- 

 roughly in air. When dry it is mounted in balsam 

 in the usual manner. 



Sections of hardened tissue are treated in the same 

 manner, and the bacillus is shown by this method 

 equally well in sections hardened in spirit and chromic 

 acid 



We consider this an excellent modification of the 

 older methods, and although the photograph of the 

 bacillus anthracis in the frontispiece, was prepared 

 by Elrich's original method, the results obtained with 

 the tubercle bacillus, by the modified plan, were 

 superior. 



Bone and all substances containing an organic 

 basis impregnated with earthy salts may be softened 

 by dissolving out the latter by prolonged maceration 

 in dilute acid, their consistency after this treatment 

 will allow of their being cut in the microtome with- 

 out freezing, if embedded in paraffin and wax. 



Eocks, fossils, and bone when not softened, require 

 entirely different treatment and considerable skill 



