BEAIN. 389 



735. Cerebrum (RUTHERFORD ; from BEVAN LEWIS). Place 

 small portions of cerebrum in methylated spirit for twenty- 

 four hours in a cool place. After that put them into the fol- 

 lowing solution : 



Chromic acid .... 1 part. 



Bichromate of potash ... 2 parts. 



Water 1200 



Change the liquid at the end of eighteen hours, and then 

 once a week. Should the tissue not be sufficiently tough for 

 cutting at the end of six weeks place it in a -i per cent, solu- 

 tion of chromic acid for a fortnight, and then in rectified 

 spirit. 



736. Cerebrum (BEVAN LEWIS, The Human Brain, p. 102). 

 Methylated spirit, twenty-four hours in a cool place. Miiller's 

 solution, three days in a cool place. Then change the liquid ; 

 and after three days more change it again, or, preferably, 

 substitute a 2 per cent, solution of potassium bichromate. At 

 the end of the second week a solution of double the strength 

 may be added; and if, at the termination of the third week, 

 the mass is still pliable and of the consistence of ordinary 

 rubber, it is as yet unfit for section cutting, and the reagent 

 should be replaced by a solution of chromic acid. 



737. Brain (HAMILTON, Journ. of Anat. and PhysioL, 1878, 

 p. 254). Take a fresh brain and make a series of incisions 

 into different parts, still keeping- everything in situ ; or slice 

 it into any number of segments about one inch thick, but of 

 the whole length or breadth of the organ, as may be desired. 

 Do not remove the membranes ; they form a protection for the 

 superficial layers, and do not interfere with the hardening 

 process. The large segments are placed flat in a large vessel 

 padded with cotton ; do not put them one above the other. 

 Cover them with the following fluid : 



Miiller's fluid ... 3 parts. 



Methylated spirit . . 1 part. 



(Heat is evolved on mixing these liquids, and the mixture 

 must be allowed to cool before pouring it over the brain 

 tissue.) Put the preparations away in an ice-safe. Turn the 

 segments over next day. Change the solution in a fortnight 

 or three weeks ; or if on examining a section of one of the 

 pieces it is found that the hardening reagent has penetrated 



