BETZ's METHOD. 325 



the liquid. After a day or two it -will have lost much of its 

 alcohol, and will sink to the bottom of the vessel, which is 

 equally undesirable ; this must be watched for, and the pre- 

 paration hung up or otherwise supported.) The vessel is put 

 away in a cool place. As soon as a brown turbidity is seen 

 in the liquid, together with a brown deposit on the prepara- 

 tion, the hardening may be considered to be complete. The 

 preparation must be at once washed with water, and put away 

 until wanted in a J to 1 per cent, solution of bichromate. 



Cerebellum. Must be quite fresh, and before placing in 

 the iodine the membranes and vessels must as far as possible 

 be very carefully removed. (If the pia mater does not come 

 away freely, the organ must be macerated for a few hours in 

 iodine solution in which other preparations have been kept, 

 and which is diluted before using for this purpose). The 

 membranes havingbeen removed, the cerebellum isplaced (sup- 

 ported on cotton-wool, with which the different organs are so 

 propped up as to preserve their natural position) in solution 

 of iodine for two or three days, and fresh iodine solution fre- 

 quently added. 



The pia mater is now removed from the rest of the prepara- 

 tion, which is put back for seven to fourteen days into the 

 iodine solution. If at the expiration of this time it be found 

 that the cerebellum can be supported on the finger by the 

 vermiculus alone without bending, the preliminary hardening 

 is complete, and it is brought into a 5 per cent, solution of 

 bichromate, where it remains until fit for cutting. 



Cerebrum. The cerebrum is divided into two halves along 

 the median line of the corpus callosum, and put into the 

 iodine solution. After a few hours the pia mater is removed 

 from the fissure of Sylvius and from the corpus callosum, and 

 if possible, the choroid plexus is removed likewise. 



The preparation is now put away in the iodine solution in 

 a cool place (in summer in a cool cellar), and fresh iodine 

 added as soon as the liquid is seen to lose colour (which must 

 be watched for). After twenty-four to forty-eight hours the 

 remaining pia mater is carefully removed by means of scissors 

 and forceps from the fissures and convolutions, and one half- 

 volume of fresh iodine solution is added to the liquid. (To 

 facilitate the penetration of the liquid, wads of cotton-wool 

 are stuffed into the fissure of Sylvius, between the operculum 



