412 CHAPTER XXXII. 



and Nitrate of Silver Method. The corrosive sublimate method 

 will be given later on. 



The bichromate and nitrate of silver method has been 

 worked out by Golgi in three forms. These are known as 

 the slow process, the rapid process, and the mixed process.* 



The rapid process is the one that is the most in use at the 

 present time for researches into the distribution and relations 

 of axis-cylinders and protoplasmic processes; it may be taken 

 to be the classical method of inquiry into the finer relations 

 of the neurons in hardened tissue. 



General characters of the impregnation. The preparations 

 have not in the least the appearance of stains, and are even 

 very different in aspect from the impregnations obtained on 

 fresh tissue by the ordinary methods of impregnating with 

 nitrate of silver or chloride of gold. The impregnation is a 

 partial one, by which is meant that of all the elements, 

 whether nervous or not, that are present in a preparation, 

 only a limited number are coloured. That is the peculiar 

 quality not by any means the defect, but rather the advan- 

 tage of the method. For if all the elements present were 

 coloured equally, with the great intensity with which they 

 take the colour in this method, you would not be able to see 

 the wood for the trees, in fact you would hardly be able to 

 distinguish any detail at all in the preparations. But Golgi' s 

 method selects from among the elements present a small 

 number which it stains with a great intensity and very com- 

 pletely ; that is to say, throughout a great length, so that 

 they are both very clearly separated from those elements that 

 have remained uncoloured, such as supporting cells and the 

 like, and also can be followed out for a great distance. 



Axis- cylinders are only impregnated so long as they are 

 not medullated. In the adult the method stains nerve cells 

 and their processes, so far as these are not myelinated ; but 

 if it be wished to impregnate the nerve fibres of the cerebro- 

 spinal axis, the method must be applied to embryos or new- 



* In a recent text-book, the Leitfaden of RAWITZ, the sublimate method 

 is called " the slow method of GOLGI," and the bichromate and silver nitrate 

 method is given under the form of the slow process, and called "the rapid 

 method of GOLGI." That is a very " nice derangement of epitaphs " indeed. 

 RAWITZ further attributes the rapid method to RAMON Y CAJAL, which is 

 equally erroneous. Similar confusions are made by MEECIEE in his Coupes 

 du Systeme Nerveux Central. 



