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STUDENTS HISTOLOGY 



lift it with the needle, drain, and transfer to the saucer containing 

 alcohol. You will then be enabled to determine whether the section 

 is sufficiently stained; it should be a deep, opaque red. The alcohol 

 washes off the section, removing the adhering solution of carmine. 

 The carmine must now be fixed in the tissue, or mordanted; and 

 this you proceed to do by transferring the section to the watch - 



PIG. 19. DIAGRAM INDICATING THE SUCCESSIVE STEPS ix STAINING WITH 

 BORAX-CARMINE . 



glass containing acid alcohol. Notice the change in color, from a 

 dull red to a bright crimson, and when the change is complete, lift 

 it into the saltcellar containing clean alcohol. This dissolves out 

 the acid. Five minutes suffice for this washing, after which trans- 

 fer to the oil of cloves. 



This process does not give as sharp contrasts as the hgematoxy- 

 lin and eosin, but it is simpler and very permanent. It is best 

 to select some one process for general work, and adhere to it. 

 The acid of the carmine process must be guarded with extreme 

 care, as the smallest particle is sufficient to spoil the haematoxylin 

 solution. Look to it that the dishes are kept scrupulously clean, 

 and the sanje care must be bestowed upon the needles, forceps, 

 and all other instruments. 



Picro- carmine may be used instead of borax -carmine. The 

 sections may need to remain in picro- carmine as much as an hour 

 to become thoroughly stained. Acid alcohol is not to be em- 

 ployed after staining. In dehydrating, it is well to add some 

 picric acid to the alcohol, in order to prevent extracting the yel- 

 low stain from the specimen. 



You may, of course, stain several sections at once, providing 

 you take care to keep them from rolling up or sticking together. 



While the vessels which we have recommended will be found of 

 convenient, proportionate, and economical size for general work, 

 larger ones are sometimes needed ; and almost any glass or porce- 

 lain vessel may be impressed for duty. 



