102 



size and shape, oiled paper may be wound around the end of the 

 cork and tightly tied, the projecting hollow cylinder being long 

 enough to receive the object. The tissue may be put into the cyl- 

 inder as before, the collodion slowly poured in drop by drop until 

 the specimen is completely covered. When a film has formed, 

 place in chloroform as before. 



(b). In a paper box. When a box is required for imbedding 

 proceed as follows : The inside of the paper box should be slightly 

 oily to prevent the collodion from sticking to it. Rub upon the 

 paper that is to be folded to form the box a little vaseline, and then 

 with a cloth or lens paper remove as much as possible. Fold the 

 paper into a box of convenient size and shape. Remove the object 

 from the thick collodion and place it in the box, arranging it in the 

 manner wished with a view to sectioning it later. Pour over it 

 slowly, drop by drop or a little at a time, an 8% solution of collodion 

 until the specimen is well covered and the box sufficicently filled. 

 It is better to have a deep layer over the specimen. The 8% solu- 

 tion does not afford the best mass for cutting, so that, with large 

 objects, it is better to allow the mass in the box to thicken by evap- 

 orating it slowly under a bell-jar (aquarium jar) until it has at- 

 tained the consistency of a very thick syrup. When thick enough 

 allow a film to harden upon the surface and immerse it in a glass 

 box or jar of chloroform. 



56. Hardening and clarifying. The chloroform into 

 which the collodion mass is placed takes out the ether- alcohol and 

 hardens the collodion mass, for which a few hours is sufficient. 

 Allow the chloroform to act for 6-24 hours. If it acts long enough 

 the imbedding mass is rendered entirely transparent when no water is 

 present. The hardening action of the chloroform may be quickened 

 and itensified by carefully heating the chloroform until bubbles of 

 ether begin to come from the specimen. 



When the collodion mass is hard, whether clear or not, pour off 

 the chloroform and add castor-xylene clarifier ( 151), in which the 

 tissue is to remain until the sections are cut. 



In a few hours the collodion mass will become quite transparent 

 (clarified) and hardly discernable, so that the tissue is readily seen. 

 Sometimes, however, the collodion remains white and opaque, due 

 to the presence of moisture, and considerable time is required for its 



