36 PRACTICAL HISTOLOGY [V 



similarly one section to hgematoxylin, and two to 

 picro-carmine. The sections in hsematoxylin will be 

 stained in about a quarter of an hour, those in picro- 

 carmine in half-an-hour to an hour 1 . 



Take four watch-glasses and fill them respectively 

 Jrd full with (1) tap-water, (2) 50 p.c. alcohol, (3) 75 p.c. 

 alcohol, (4) 95 or 96 p.c. alcohol (strong methylated 

 spirit). Cover up the 95 p.c. alcohol with a watch- 

 glass to prevent evaporation. In another watch-glass 

 pour a few drops of clove oil. 



With the fine glass rod, take a section from the 

 haematoxylin and place it in tap-water for a minute, 

 gently moving it. (The section should be a fairly deep 

 blue ; if it is not, put it back in the hsematoxylin for a 

 further 10 to 15 minutes.) Place it for the same time 

 in 50 p.c. and in 75 p.c. alcohol. Leave it for 3 to 5 

 minutes in 95 p.c. alcohol. 



Tap-water is used, since the salts in it give the section a 

 bluer (and deeper) tint. But it causes a slight precipitate in the 

 hsematoxylin ; this is nearly always washed off the section by the 

 method given here. Very thin sections, those liable to break up, 

 and those which are sticky, should be passed through all the 

 fluids flat on a lifter instead of on a glass rod, and in this case 

 it is best to use distilled water before tap- water so as to avoid the 

 chance of a precipitate. Further, 30 p.c. alcohol may be used 

 between water and 50 p.c. 



If the section is folded when in 50 p.c. alcohol, it 

 should be transferred from 50 to 75 p.c. and from 75 to 



1 Delafield's haematoxylin (undiluted) stains sections in 1 to 2 

 minutes, Ehrlich's acid hsematoxylin in 3 to o minutes, and Mayer's 

 carmalum in ^ hr. to 1 hour. The rate of staining varies with 

 the agent used to fix the tissue. Tissues fixed with alcohol or 

 mercuric chloride stain more quickly than those fixed in a fluid 

 containing chromic acid or osmic acid. 



