CHAPTER XX 

 HISTOLOGIC TECHNIC 



The satisfactory examination of the tissues with the aid of the mod- 

 ern microscope requires certain preparatory steps which are in certam 

 cases very simple, in others very complicated. The present chapter deals 

 briefly with the more important and simpler methods, and the general 

 principles upon which they are based. 



THE EXAMINATION OF FRESH TISSUES 



Certain tissues may be examined immediately after they have been 

 removed from the body. This method is applicable to blood, lymph, 

 scrapings from the spleen, liver, uterus, and similar organs, small frag- 

 ments of muscle, connective tissue, etc. 



A small drop of blood may be collected upon the under surface of a 

 cover glass, which is then quickly dropped upon a glass slide and 

 examined at once. The glass must be thoroughly cleaned, otherwise a 

 thin preparation can not be obtained. Slides and covers should be 

 washed in very dilute hydrochloric acid (about 10 per cent.), then 

 washed in running water for several hours, and finally rinsed in 95 per 

 cent, alcohol. Ordinarily slides and cover glasses can be sufficiently 

 cleaned by simply dipping in alcohol and drying with a linen cloth. 



Scrapings from the epithelium of the mouth, or from similar mucous 

 membranes, may be prepared in the same manner as blood, and ex- 

 amined while still suspended in their own fluids. Most tissues, however, 

 are not sufficiently well moistened for examination after this manner; 

 the preparation must then be diluted with some inert fluid. Normal 

 saline solution may be used for ibis purpose; the following formula is 

 recommended : 



Sodium chlnnd 0.7'.") to ().!) grm. 



Distilled water 100 c.c. 



720 



