372 NERVES. 



be cut into lengths of J to 1 cm., which are put back into the 

 liquid. 



Four hours after the first immersion of the nerve in the 

 mixture begin to put the pieces into nitrate of silver solution, 

 transferring a certain number of pieces every three hours, 

 so as to be sure that some of them shall have had a bi- 

 chromate bath of a proper duration. (This duration may, 

 roughly speaking, be said to lie between six and twenty-four 

 hours.) 



The strength of the nitrate of silver solution is 0*50 per 

 cent. The duration of the silver-bath must not be less than 

 eight hours ; it may be indefinitely protracted. 



Dehydrate, clear with turpentine, mount in dammar. 



The method is more expeditious and easier of application 

 than the bichromate and silver nitrate method, and the results 

 are somewhat more precise, but the preparations do not keep in 

 dammar (without special precautions, to be discussed below). 



These two methods serve for the demonstration in peripheral niedullated 

 nerve-fibres of the funnel-shaped coils of sustaining filaments discovered by 

 Kezzonico in the medullated fibres of the spinal cord. 



In all methods for the demonstration of the funnels it is important to 

 observe the utmost delicacy of manipulation, and in particular, the fibres 

 must not be stretched; their stretching is a weak point in the methods of 

 Kanvier (Traite, p. 718). 



Modifications of Golgi's Chromate of Silver Method. 



707. Critique of GOLGI'S Method. The above-described 

 methods have been found extremely valuable in the most 

 various departments of nervous anatomy. They have given 

 brilliant results in the study of peripheral nerves and their 

 origins or terminations, and in the study of the relations of 

 fibres and cells in the central nervous system. It has been 

 found, at the same time, that they have the defect of con- 

 siderable uncertainty in the production of the desired reac- 

 tion, and a still greater uncertainty in the preservation of the 

 stain. These defects have given rise to a most elaborate 

 discussion, which unhappily has not as yet led to very satis- 

 factory results. 



Golgi' s method is apparently (but this is by no means 

 certain) a double decomposition method, based on the com- 

 bination of the bichromate of potassium in the tissues with 



