CHAPTER XXX 

 TECHNIQUE 



THE satisfactory examination of the tissues with the aid of the 

 modern microscope requires certain preparatory steps which are at 

 times very simple, at other times very complicated. The present 

 chapter will deal very briefly with the more important of the sim- 

 ple methods and the general principles upon which they are based. 



THE EXAMINATION OF FKESH TISSUES 



Certain tissues may be examined immediately after they are re- 

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

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

 bits 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, then washed in 

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

 alcohol. 



Scrapings from the epithelium of the mouth, or from similar 

 mucous membranes may be prepared in the same manner as blood, 

 and examined while still suspended in their own fluids. Most tis- 

 sues, 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 this purpose ; 

 the following formula is recommended : 



Sodium chlorid 0.75 to 0.9 grm. 



Distilled water 100 cc. 



A 40 per cent, solution of glycerin in distilled water may be 

 used for the same purpose ; better still, the tissues may be sus- 

 pended in a mixture of equal parts of alcohol, glycerin, and dis- 

 tilled water. The author has found this mixture to be especially 



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