406 



add one part of glacial acetic acid to twenty parts of 

 stock. Fix until the tissue is opaque throughout (one 

 or more hours). Wash in water till washings colourless 

 and free from acid (an hour more or less). Preserve 

 in eighty per cent, alcohol. This is an excellent 

 general fixative. 



N.B. The sublimate is best removed from the sections before 

 staining by Lugol's solution. 



8. Lugol's Solution. 



Iodine ro gr. 



Potassium iodide 2*0 gr. 



Water loo'o 



TREATMENT AND PRESERVATION OF FIXED TISSUES 



1. The best method, if possible, is after washing 

 out the fixative to imbed the tissue at once or after 

 some days in paraffin (p. 46). Pour the paraffin out 

 into paper boats, small match boxes, etc. The tissues 

 will then keep indefinitely. 



2. The next best method is after washing and 

 dehydrating to pass into cedar wood oil and preserve 

 in the oil. 



3. If neither of these methods is possible, then 

 after washing (and passing through increasing strengths 

 of alcohol, if required) to preserve in rectified spirit, 

 or eighty-five per cent, alcohol or methylated spirit. 

 The staining of tissues is somewhat imperfect after 

 long preservation in alcohol. 



WASHING THE FIXED TISSUES 



If the fixative used has been an alcoholic one, then 

 wash out in absolute alcohol (or spirit). (This, as will 

 be seen, saves a good deal of subsequent trouble.) 

 If the fixative has been a watery one, then it is 



