AND CONTENTvS OF THE MOUTH. 87 



the rod, until the layer of the Leptothrtx, spreading in every direc- 

 tion, reaches the edges of the cover, and the redundant liquid 

 trickles down by its side. The preparations, stained with aniline 

 colours, become a little hard (perhaps owing to the alcohol in it) ; 

 but yet they get thinned enough. Those treated with the iodine, 

 and especially those treated with picric acid, or the colourless ones, 

 being more flexible, become more easily thinned. 



In order to see the fructifications in a fair quantity and dis- 

 tinctly, it is necessary to wait some time. Naturally, those on the 

 edges of each tiny island are seen more distinctly, but all do not 

 show them, because many of the islands contain only filaments or 

 bud-growths. Some are wasted, and others overlie one another, 

 mixing their relative edges together. Now, in those edges with 

 exuberant fructifications, these at first are close together ; but the 

 preparation in time partially dries up, and on pouring on it a fresh 

 drop of distilled water the cover-glass slightly rises, and then the 

 tufts of ears begin to open ; the ears separate one from another, 

 and (in preparations with picric acid) several may be counted in, 

 the visual field. Such observations can be continued for several 

 days by adding to the preparation from time to time a drop of 

 distilled water. 



To demonstrate the productions by points, the method of 

 working must be modified, as we shall see in Section 4. 



Saliva. — To get the saliva as far as possible free from froth 

 and air-bubbles, the following plan should be adopted : — Let the 

 patient before tasting food spit on a well cleaned glass rod, held 

 horizontally ; then incline it so that the saliva shall run down 

 towards the hand, parting, in its course, from the small air-bubbles, 

 which, being lighter, adhere to the rod and stop the froth. When 

 a drop of saliva has gathered on the handle, it may be taken off 

 by the point of a second rod and carried directly on to the slide 

 (if we wish to examine it with the patina deiitaria and then mix 

 them together); or, if we wish to examine them separately, it 

 should be immersed in a drop of colouring mixture, already placed 

 on the slide. As soon as the preparation is sufficiently coloured, 

 it should be covered without washing. If the colouring is very 

 weak, with slight vestiges of colour, the vibrating motion in the 

 salivary corpuscles will be better detected. 



