438 HISTOLOGICAL TECHNIQUE. 



I. Examination of sputa for elastic fibres. In pulmonary disease 

 involving a destruction of pulmonary tissue and the appearance of 

 fragments in the expectoration, elastic fibres from the alveolar walls 

 may frequently be found in the sputa : 



Fill a test-tube one-third full of sputa, add five or six drops of 

 36 per cent, potassium hydrate solution, and boil the mixture for 

 three or four minutes. Add an equal bulk of distilled water. 

 Divide the contents of the tube between the two tubes of the cen- 

 trifuge and precipitate their contents. If elastic fibres Avere pres- 

 ent, they will be found either in the sediment or in the scum on the 

 top of the fluid. 



9. Methods of Maceration. 



a. One-third alcohol. 



95 per cent, alcohol, 35 cc. 



Distilled water, 65 " 



This dilute alcohol is excellent for the separation of epithelium 

 from the surfaces of mucous membranes. The fresh tissues are 

 placed in the alcohol for a day or two, after which the cells can 

 easily be detached and separated by shaking. The cells are well 

 preserved, and may be stained with methylene-blue or alum-car- 

 mine. 



b. Potassium hydrate. 



Potassium hydrate, pure by alcohol, 36 grams. 



Distilled water, 64 cc. 



The solution should be cold before use. It cannot be filtered 

 through paper ; but if not clear, should be decanted from any sedi- 

 ment, or a fresh solution prepared. Maceration takes place very 

 quickly in this solution. The tissues can usually be teased apart 

 within fifteen to thirty minutes. They must be examined in the 

 potash solution without dilution, as the addition of water quickly 

 destroys the tissue-elements. For this reason the specimens to be 

 macerated should be placed in several times their bulk of the pot- 

 ash solution ; otherwise the water they contain will dilute the pot- 

 ash. Permanent mounts cannot be made. 



c. Chromic acid. A solution of 1 part of the acid in 10,000 

 parts of distilled water will facilitate the teasing apart of tissue- 

 elements which have macerated in it for one to several days. After 

 careful washing on the slide alum-carmine alone, or followed by 

 picric acid, may be used for staining. 



