CELLOIDIN EMBEDDING 273 



tiine-consuniing tliaii is the case witli paraffin sections. Solutions 

 of celloidin in an cthcr-alcohol mixture are utilized in celloidin 

 infiltration. 



Celloidin is furnished in small solid i)ieces. Remove all the 

 pieces from a 1-ounce bottle, dry them thoroughly, and place in 

 a glass-stoppered bottle, adding about 150 cc. of absolute ethyl 

 alcohol and 150 cc. of sulphuric ether. Stopper the bottle and 

 keep the stopper free of the solution at all times. It will take 

 several days before the celloidin has completely dissolved. This 

 will make a stock solution of concentrated celloidin, which we will 

 call the No. 1 solution. When it is in complete solution, make 

 stock solution No. 2 l)y diluting part of No. 1 with about three times 

 as much of equal parts of absolute alcohol and ether. Also make 

 stock solution No. o by diluting solution No. 1 with about ten 

 times as much of equal parts of al)Solute alcohol and ether. Keep 

 a supply of each of these three solutions on hand, taking care that 

 each is kept in a tightly stoppered bottle, as evaporation of the ether- 

 alcohol soon changes a thin solution to a thicker one. 



Tissue in Bouin's or Zenker's fluid can be embedded in celloidin 

 as well as those especially designed for nerve study. It is well to 

 use thin pieces, i. e., about 0.3 cm. thick, because infiltration pro- 

 ceeds slowly and with difficulty. Each successive fluid presently 

 named must penetrate the tissue piece, and as the size is increased 

 the time needed must be extended. It is suggested that the student 

 at first use a piece of soft tissue, such as the liver, about 0.5 by 0.5 

 by 0.3 cm., and follow the longer time period given in the following 

 table. We will suppose that the tissue has been fixed in Bouin's 

 fluid, washed, and taken from 70 per cent alcohol, where it has been 

 preserved. The process takes place at room temperature and in 

 bottles that can be tightly stoppered. The time can be shortened 

 by keeping tightly covered bottles at a temperature of 40" C. 



Celloidin Embeddixc; Method. 



From 70 per cent alcohol to 95 per cent, for two hours. 



From 95 per cent to fresh 95 per cent alcohol, for one hour. 



From 95 per cent alcohol to 100 ])er cent alcohol, for two hours. 



From 100 per cent alcohol to fresh 100 per cent, for tweh'e to 

 twenty-four hours. 



From 100 per cent alcohol to one-half absolute alcohol + one- 

 half ether, for twelve to twent\'-four hours. 



IS 



