- 79 — 
first it is well to wash them in a weaker solution (.5 %) of silver- 
nitrate and then afterwards place ttiem in stronger solutions (up to 
I 7o)- After one day the staining is generally complete. If one 
wishes, however, to keep the preparations for some time before cutting 
them, they must be læpt in a clean solution of siiv^er-nitrate. It is 
best, of course, to keep them in opaque bottles; kept in that way 
they are not destroyed even for months. If we wish to take sec- 
tions we may cut tliem, directly from the silver sokition, with a 
sharp razor, under alcohol. The sections need not be very thin ; 
when cut, they may be, preliminarily, examined at once in glycerin, 
if the staining proves to be a good one — i. e. if ganglion cells with 
all their processes, and nerve-tubes with their ramifications, appear 
quite dark or black on a transparent field, — then new sections 
are made and washed well in alcohol of about 90 or 96 7o- 
This washing I have usually performed in the foUowing way: 
the inferior end of a fun nei with a rather wide tube is closed with 
a plug of cotton so as to form a kind of filter. The sections are 
placed upon the cotton, then the tube of the funnel is filled with 
alcohol and another plug of cotton is pushed down the tube to 
a certain distance above the sections: the sections are thus situated 
in a small tube-chamber filled with alcohol. When now, however, 
the body of the funnel is filled with alcohol, a stream will slowly 
filter through this chamber and thus the alcohol in it will be con- 
stantly renewed. By putting more or less cotton into the tube one 
may regulate the velocity of the stream through the chamber. When 
the sections are sufficiently washed (in 4 — 8 hours) they are placed in 
absolute alcohol. If there are many sections, the alcohol is changed 
once or twice. Then (after some hours) the sections are placed for 
some time (some hours or more, even a day) in pure turpentine which 
has to be changed several times. Then they are placed on the slide 
in dammar-resin dissolved in turpentine and protected by no coverglasses 
if you wish to keep the preparations for a long time. The dammar 
is at once dried in a warmbath or in an incubator, where the 
turpentine is very rapidly evaporated and the dammar becomes quite 
hard and smooth; a coverglass prevents the turpentine and other 
volatile oils evaporating. If the dammar is not quite smooth in 
some places after drying, a little more dammar is added to these 
places, and the drying repeated. A very good method of mounting 
is, of course, that recommended by Prof. GOLGI, it is, however, 
a. little more complicated. Prof. GoLGi mounts the sections, in 
dammar, on coverglasses, the coverglasses are again mounted on 
