9 6 

 Living tissue 



v 



Fixing 

 Hardening in 

 alcohols (50-67-82-95 %) 



Dehydration 

 (in 95-99 % alcohol) 



Paraffin Method 



Cedar-oil Clearing . 



Melted paraffin Infiltrating < 



Collodion Method 



Ether-alcohol 



Thin collodion 

 (1-2 % solutions) 



V 



Thick collodion 

 (6-8 % solutions) 



Paraffin mass 4 



cooled quickly Imbedding 



( . v 



I Collodion hardened 

 in chloroform 



\ I 



Collodion block 

 clarified 



In Paraffin --------- Sectioning ---------- In Collodion 



THE PARAFFIN METHOD. 



42. As seen by the above scheme, the aim is to fill all the 

 interstices of the tissue with paraffin of the right degree of hardness 

 to have it cut well. Paraffin is not soluble in water or alcohol, but 

 is soluble in a number of fluids which in turn are miscible with alco- 

 hol. Hence the following steps are necessary : (i) the tissue must 

 be first water-rid, thoroughly dehydrated with strong alcohol; (2) 

 freed from the alcohol, cleared by a fluid that mixes with melted 

 paraffin, which (3) takes the place of the clearer in the tissue, 

 infiltrates it, filling the spaces ; (4) finally, the tissue is imbedded in 

 paraffin of the right degree of hardness, the mass cooled, and it is 

 ready (5) to cut, or section. 



