Brain Presei'vation ,399 



dration in repeated changes of ninety-five per cent, alcohol, 

 immerse the brain in a mixture of : 



Turpentine 3 parts, 



Castor oil i part, 



until it becomes tolerably translucent (one or two weeks) 

 changing the solution if it becomes cloudy, then transfer to 

 pure castor oil for a week or two. Allow it to drain on a layer 

 of cotton covered with absorbent paper until the surface dries 

 and then paint it over a few times with an alcoholic solution of 

 bleached shellac. The specimen soon becomes firm and re- 

 quires no special attention when once it has become dry. This 

 process differentiates alba and cinerea well. (See Plate). 

 The brain sections or dissections should be made before im- 

 mersing in the turpentine-oil mixture. It will be found that 

 the alba becomes translucent first, the preparation at this par- 

 ticular stage may then be put into the pure castor oil until 

 thoroughly penetrated and subsequently drained and shellaced. 

 The castor oil may be used repeatedly and costs only one-half 

 as much as glycerin. 



Some shrinkage occurs, the dry specimen losing about one- 

 fourth of its volume after it has left the liquid. It should be 

 remembered that the brain consists of eighty-eight per cent 

 of fluid and that the possibilities of evaporation and the re- 

 placement of this natural liquid by an artificial one as in 

 dehydration render some shrinkage inevitable. It is not 

 feasible therefore to harden a brain rapidly without some con- 

 densation of tissue, the main point is to harden the specimen 

 without distortion or to have the shrinkage evenly distributed. 

 Theoretically the shrinkage might be les.sened or entirely 

 obviated if each fluid or mixture into which the brain is 

 immersed could be kept at the same specific gravity as the 

 brain itself, and replace equally its normal fluid. This does 

 not seem to be practicable where dehydration is necessary. 

 The dry process has given good results on delicate fetal brains, 

 it seems to strengthen them so that they may be readily 

 handled, but great care must be taken in transferring them 

 through the different fluids. If breakage should occur the 



