INTRODUCTION. 9 



A him Carmine. Boil one half to one per cent, 

 of pulverized carmine in a nearly saturated solution, 

 in water, of ammonia or potash alum for half an 

 hour, allow the fluid to cool, filter and add a few 

 drops of carbolic acid to the filtrate as a preserv- 

 ative. Keep in a well stoppered bottle. This 

 staining fluid is nearly a pure nuclear staining, giv- 

 ing purplish-red shades. Usually it requires fifteen 

 minutes to half an hour for staining, but the 

 specimens may remain in it for twenty-four hours 

 or longer, as it does not overstain. This is an 

 excellent fluid for staining in toto. 



Eosin. This substance stains tissues more uni- 

 formly than many other dyes, and is especially 

 valuable when used in connection with other color- 

 ing agents, such as haematoxylin, which stains the 

 cell nuclei more deeply, since by this method of 

 double staining we have certain elements exhibiting 

 one color, others another. Eosin may be conveni- 

 ently used either in aqueous or alcoholic solutions 

 of one to one hundred. 



METHODS OF PREPARING SPECIMENS FOR STUDY. 



Certain fluid tissues, such as blood, lymph, etc., 

 are fitted for study, either fresh, or after suitable 

 preservation, when a drop is placed on a slide, and 

 covered. Certain tissues occur in the form of mem- 

 branes, of sufficient thinness to admit of study with- 

 out other manipulation than spreading them out 



