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coarse nerve fibre meet, it is difficult in short distances, to say de- 
finitely where gall capillary begins and nerve fibre ends; hence those 
areas in which the capillaries are not stained are the only ones in 
which it is absolutely certain that we are not dealing with both nerve 
and capillary at the same moment. ‘Terminations are only to be 
distinctly seen where the impregnation of the capillary is wanting, so 
far as the intra-lobular structures are concerned. 
1) In our research on the renal nerves (5), we found that an 
ammonium salt — the picrate — added greatly to the clearness with 
which the finer nerve endings were rendered apparent. On using the 
same salt with the hepatic organ, we found that it was exceedingly 
uncertain in its action, and could not be relied upon to furnish any 
clear staining of the nerve fibres. 
A further series of experiments were then undertaken with other 
media, and picric acid gave more constant as well as finer details 
than any of the other chemicals experimented with. A further very 
important point was also gained, namely, that the gall capillaries were 
not so uniformly stained throughout the sections, as by the ordinary 
rapid GoLaI method, numbers of spaces with uncolored capillaries 
being obtained in nearly every section, and, as the majority of the 
nerve filaments run with the capillaries, the importance of this feature 
may be readily estimated. 
The method is shortly as follows: The tissue is cut into slices 
not over one and a half millimetres in thickness, and while quite 
warm, is immersed in a saturated solution of picric acid, diluted with 
an equal volume of warm water. After remaining in this solution for 
from fifteen to thirty minutes, by which time the acid should have 
penetrated through the tissue, it is immersed without previous washing 
in the hardening fluid, where it remains for forty-eight hours or 
longer. The formula for the hardening medium is somewhat different 
from that in ordinary use, and is composed of: 
Aqueous Solution Kalium bichromate 
(saturated in the sun-light) 100 parts. 
Solution of Osmic Acid 2 °/, 16 parts. 
The solution is to be made several days before it is used and exposed 
to the full sun-light to age. All specimens are however to be 
hardened in absolute darkness at a temperature not lower than 25 C, 
and after the 48 hours have expired are treated with the silver so- 
lutions of 0,25 and 0,75°/, in the usual manner, and allowed to re- 
main them for 5 to 6 days or longer. Then, after very rapid washing 
in running water, they are rapidly dehydrated, immersed for a few 
