94 A MANUAL OF BACTERIOLOGY 



air-bubbles. To remove these bubbles small air- 

 pumps have been devised, but they are not to be 

 recommended ; ' the only thing to be done when an 

 air-bubble lodges in a cavity of the section, and 

 refuses to move in any way by gentle pressure, is 

 to lift the cover-glass, and transfer the section to 

 oil of cloves, and then remount it.' As the mount- 

 ing of sections may be performed in the summer, 

 the xylol balsam is much thinner than usual (due 

 to the heat), and therefore takes a much longer 

 time to set. In such cases a mounting clip (Fig. 29) 

 is useful to keep the cover-glass from moving, i.e. 



until the balsam sets. 

 After this the slide should 

 be sealed with Hollis' 

 glue, or some other ce- 

 menting agent, as already 

 described. 1 



FIG. 29. MOUNTING CLIP. . Methods of Introduc- 



ing Microbes into Living 



Animals. In such experiments guinea-pigs, rabbits, 

 mice, fowls, etc., are used. Pure cultivations of 

 microbes and infectious matter are introduced into 

 the animal body by the following methods : 



(a) Inhalation. 



(b) Swallowing. 



(e) Direct inoculation. 



(d) Special operations. 



(a) An animal is made to inhale the infectious 

 matter, etc., disseminated by means of a spray ; (b) 



1 For further information see Martin's Manual of Microscopic 

 Mounting. 



