THE PREPARATION OF SECTIONS 



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(2) Hardening of Tissues. 



Place the tissue in three strengths of alcohol successively, 

 viz. : 50 per cent., 75 per cent., and absolute, the tissue 

 remaining in each twenty-four to forty-eight hours. 



If one desires to keep the tissue, place in 70 per cent, alcohol. 



Cut from the tissue small blocks 10 to 20 mm. square and 

 immerse in alcohol. 



(3) Freezing of Tissues. 



Place the blocks of tissue in an open vessel and allow water 



Microtome, Cathcart's, with spray bellows. 



to run into it for two hours to remove the alcohol, then soak 

 in a syrupy m.ucilage of gum acacia with a little carbolic acid. 



Place it on the plate of the freezing microtome, a little 

 mucilage is added and the whole frozen. The sections are 

 cut by the knife moistened with A\ater and brushed into 

 tepid water with a camel-hair brush. 



These can now be stained or preserved in 70 per cent, alcohol. 



(4) Embedding of Tissues. 



After hardening place in absolute alcohol twelve to twenty- 

 four hours, then in pure xylol for the same time, then in a 



