TECHNIC 507 



Use smaller or thinner portions of tissue if possible and place in a rather small quan- 

 tity of the fluid. Do not change the fluid. Fix for twenty-four hours to ten days. 

 BB. Same as (B), except that the tissue should be washed for a time in clean tap 

 or distilled water and the iodide treatment dispensed with. Subsequent steps are 

 the same. 



THIRD EXAMPLE 



Another variation that should be tried is as follows: Treat tissue according to 

 (A) and (B). 



HH. Stain for twenty-four hours in a solution of borax carmine. Decolorize for 

 twelve hours, with frequent changes, in 70 per cent alcohol to which hydrochloric is 

 added (6 drops to each 100 cc.). 



Then proceed as in (C), (D), (), (F), and (G), except that the alcohols should be 

 omitted in this latter step. As the sections are already stained, they may then be 

 mounted as in (/), except that the first treatment (with alcohol) may be omitted as the 

 sections are already free of water. 



FOURTH EXAMPLE 



Celloidin embedding should now be practiced as follows. Proceed, with the same 

 tissue, as in (A), (B), (HH), and (Q. 



/. Place in a quantity of celloidin dissolved in equal parts of ether and absolute 

 alcohol. The amount of celloidin should be from i to 2 per cent. This should be in 

 a well-stopped bottle, and a long treatment of days or even weeks is beneficial. Forty- 

 eight hours will do. The strength of the celloidin solution should be increased to 

 6 per cent, and finally the object should be placed on the end of a cork surrounded with 

 a covering of thick celloidin solution, and as it becomes firm on the surface, plunged 

 into pure chloroform (on the carrier) for an hour or more, to harden. 



K. When hard, it should remain in a mixture of cedar oil (or cedarwood oil) 

 and chloroform, equal parts, for another hour, when the whitened celloidin will become 

 clear. Sections may now be cut with a knife wet in the chloroform-cedar oil mixture. 

 A soft brush must be used to keep the knife flooded, and chloroform must often be 

 added to compensate for evaporation. When the cedar oil is in excess, the celloidin 

 softens or even melts. 



L. The free sections may be floated on a slide with a brush, drained, and at 

 once mounted in balsam. They are already dehydrated and cleared and need 

 only the balsam and a cover glass. 



One more method should be carried out in the concrete as follows in this 



FIFTH EXAMPLE 



Prepare a bit of rat testis by fixation, etc., as in (A), (B), (HH}, and then restain 

 it in Mayer's haemalum (see Lee) for twelve to eighteen hours. Extract the stain for 

 six to ten hours in i per cent alum water (common alum). Dehydrate (C), infil- 

 trate with celloidin (/), and clear as in (K}, except that the specimen is free and not 

 placed on a cork or other carrier. 



Now embed (F) and cut thin sections ; these may be either handled free (L) by 

 dissolving the paraffin or floated with water on the slide (G) and mounted, or 

 even fastened to the slide and restained before mounting if the stain has proved unsat- 

 isfactory. 



A favorite method in medical work, where fairly thick sections from the tissues of 

 mammals are desired, is to infiltrate unstained material with celloidin, harden in 



