THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



YoL. Y. 



Washington, D. C, November, 1884. 



No. 11. 



The Microscopic Investigation of 

 the Brain and Spinal Cord. 



BY W. T. COUNCILMAN, M. D., AS- 

 SOCIATE IN PATHOLOGY, JOHNS 

 HOPKINS UNIVERSITY. 



The means which have been gen- 

 erally used up to the last year or two 

 for the microscopic investigation of 

 the central nervous system have been 

 very imperfect. Carmine has been 

 generally used as a staining reagent, 

 and it stains most of the nerve fibres 

 very well. It is also unequalled for 

 staining the large ganglion cells in the 

 grey matter, but the fine nerve fibres 

 in this are not brought out, for they 

 are einbedded in a substance which 

 stains just as do the axis cylinders. 

 The same holds good also for haima- 

 toxylin and the most of the anilin 

 coloi's. Other methods, as the gold 

 chloride staining, and that recom- 

 inended by Exner of osiTiic acid, after 

 previous treatment with ammonia, 

 give much better results ; but the nec- 

 essary manipulations require great 

 care, and the results are very uncertain . 

 The gold method can only be used on 

 perfectly fresh material, and hence is 

 practically out of the question in hu- 

 man tissues ; preparations by both 

 this and osmic acid have the further 

 disadvantage of changing in a short 

 time. 



For any investigation of the ner- 

 vous system, whatever be the method 

 used, it is necessary to obtain the 

 specimens at a much earlier period 

 after death than autopsies are usually 

 inade. No tissue in the body suffers 

 so much from post-mortem change as 

 the nervous tissues, and although, in 

 some cases, tolerable results may be 



obtained when twelve or fourteen 

 hours have elapsed between the death 

 and the autopsy, it is in all cases bet- 

 ter to obtain the material after only 

 four or six hours have elapsed. 



The cord should be taken from the 

 body entire, still enclosed in the dura 

 mater, and all pulling and hauling on 

 the cord be avoided. The dura can 

 be grasped with a pair of forceps, and 

 the small amount of traction neces- 

 sary in raising the cord to cut the 

 spinal nerves be made upon this. 

 After the cord is removed the dura 

 must be slit up anteriorly, and with a 

 sharp knife incisions must be made 

 through the cord at intervals of one 

 inch. The vv^hole cord should then 

 be suspended in Midler's fluid in a 

 tall vessel. The pieces of brain to 

 be examined should not be more than 

 I to i|^ inches square, should be cut 

 with a sharp knife, and handled as 

 littJe as possible. The medulla and 

 pons may be left entire. The pieces 

 of brain or medulla should be laid on 

 absorbent cotton in a vessel previously 

 filled with Midler's fluid. Under or- 

 dinary circumstances it takes for such 

 tissues to acquire the proper degree 

 of consistency more than two months, 

 but the process of hardening can be 

 shortened in various ways. We can 

 either add to the Miiller's fluid a 

 small quantity of copper sulphate, or 

 substitute for it the fluid of Erlicke : — 



Potassic bichromate ......... 3.5 



Copper sulphate .5 



Distilled water 100. o 



The addition of the copper gives a 

 slight greenish tint to the tissues, but 

 does not interfere with the staining. 

 In this fluid tissues become sufliciently 



