140 THE MICROSCOPIST. 



from each other. The fluid employed for this purpose is 

 acetic acid. When this is added to a fluid where pus is pre- 

 sent, the globules swell up, and several large, transparent nuclei 

 make their appearance ; but when it is added to a fluid where 

 mucus is present, the globules also enlarge and show their nu- 

 clei, but not so plainly as the pus, and the liquid, termed liquor 

 muci, in which the globules float, is instantly coagulated into a 

 semi-opaque corrugated membrane. 



The presence of fatty matter is ascertained by sulphuric ether, 

 which readily dissolves the oily part, and leaves the membran- 

 ous cell-wall untouched. 



Earthy matters require the aid of the acids for their solu- 

 tion ; these should be added in a dilute form, so that their sol- 

 vent action may be more easily witnessed. 



Solid parts, as tumors, &c., that are to be examined as 

 transparent objects, with high powers, require to be cut into 

 very thin slices, and separated, if necessary, by the needle- 

 points. The sections should be placed on a slide, and a little 

 serum or white of egg in water, added, in order to float out 

 certain of the parts, and to lessen the refraction of the light at 

 the edges of the object. Water will answer the purpose for some 

 of the hard tissues, but where nucleated or other cells, and 

 nervous matter, are present, its use is inadmissible. 



It is necessary to state, that the examination of all morbid 

 structures should be made as soon as convenient after their re- 

 moval from the body, as changes of form in the softer sub- 

 stances speedily take place ; but if some time has elapsed, the 

 part from which the sections are taken should be at some dis- 

 tance from the surface, in order that they may be as little 

 altered as possible by the action of the air. 



The foregoing directions have been condensed from those of 

 Mr. Quekett, to whose book we have already been much in- 

 debted during the progress of this work. 



