3 o4 COLLODION METHOD [ CH. X 



The sections are now ready for the subsequent staining and 

 other operations to make a finished slide. One has to remember 

 that if mucicarmin (§ 389) is to be used in staining, the prepara- 

 tion must not be collodionized as carmin stains collodion. 



THE COLLODION OR CELLOIDIN METHOD OF SECTIONING 



§ 451. Collodion Method. — In this method the tissue is 

 thoroughly permeated with a solution of collodion which is after- 

 ward hardened. "Unlike the paraffin of the paraffin method, the 

 collodion is not subsequently removed from the tissue, but always 

 stays in the sections. It is transparent and does no harm. 



The fixing and dehydration with 95% alcohol is the same as 

 for the paraffin method (§§ 430, 440). 



The paraffin method gives thinner sections than the collodion 

 method and for series and large numbers of sections is superior. 



The collodion method requires no heat for infiltration, and it 

 does, not render the firmer forms of connective tissue so hard and 

 difficult to cut. It is especially adapted for making sections of 

 large pieces of tissue or organs and when thick sections are desired. 

 It is not easy to cut sections less than 10 ju with collodion, while 

 with paraffin it is possible to make good ribbons of small objects of 

 delicate texture 2 /< to 3 ju in thickness. With a very sharp knife 

 and small delicate object, and one of the better forms of microtomes 

 one can cut short series in i/< sections and get perfect ribbons. 



Collodion sectioning is sometimes denominated the ' ' wet 

 method ' ' as the tissuejand sections must always be wet with some 

 liquid, while the paraffin method is called the " dry method" as the 

 tissue once infiltrated with paraffin keeps in the air indefinitely and 

 in cutting the sections no liquid is used. 



§ 452. Infiltration with Ether Alcohol.— Transfer the 

 piece of tissue to be cut from 95% alcohol to a mixture of equal 

 parts of sulfuric ether and 95% alcohol and leave in this for a few 

 hours or a day or more as is most convenient. This is to soak the 

 tissue full of a solvent of the collodion. 



§ 453. Infiltration with 1%% Collodion. — Pour off the 

 ether-alcohol from the tissue and add i}4% collodion. Leave in 

 this over night or longer if the piece of tissue is large. 



