CH.X] COLLODION METHOD 305 



§ 454. Infiltration with 3% Collodion. — Pour off the 1%% 

 collodion and put in its place 3% collodion. Leave the tissue in 

 this half a day or longer. 



§ 455. Infiltration with 6% Collodion. — Pour off the $% 

 and add 6% collodion to the piece of tissue. For complete infiltra- 

 tion with this thick collodion leave the tissue in it for one day at 

 least. If the object is large it is advantageous to leave it in for a 

 week or two. 



Fig. 245. Slender dish for hardening the collodion in 

 chloroform or in alcohol. {Cut loaned by the Whilall, Tatum 

 Co.). 



§ 456. Infiltration and Imbedding in 8% Collodion. — Pour 

 off the 6% and add 8% collodion. Leave the tissue in this at least 

 one day, and as much longer as possible up to two or three weeks 

 if the piece of tissue is large. 



(A) For imbedding small pieces use a piece of wood, (deck 

 plug) , vitrified fiber, glass or a good cork for a holder and cover the 

 end with 6% collodion and let it get well set in the air, then put 

 the piece of tissue on the holder and drop 8% collodion upon it at 

 intervals until it is well covered all around. If one takes consider- 

 able time for this the collodion thickens greatly in the air. This is 

 an advantage for it gives a denser block for sectioning. After the 

 collodion is pretty well set, place holder and tissue in a vessel with 

 chloroform to harden. One can put the preparation into the chloro- 

 form or if the vessel is tight it may be above the chloroform, the 

 vapor then acting as the hardener. 



(B) Imbedding in a box. — If the object is of considerable size 

 it is best to use a paper box for imbedding as with paraffin. If a 

 very small amount of vaseline is rubbed on the inside of the box it 

 prevents the collodion from sticking to the paper. 



Put first some of the 8% collodion in the box and let it remain 

 in the air until nearly solid, 2 to 3 minutes. Then arrange the 

 specimen to be cut as for imbedding in paraffin, and add gradually 

 8% collodion until the object is well covered. Let the box stand 

 for a few minutes in air, then place it in a dish like a Stender dish 

 (Fig. 245) and pour some chloroform on the bottom of the dish. 

 Cover and the collodion will harden partly by the chloroform vapor 



