150 | J. B. Johnston 
series of unbroken sections of suitable thinness, on account of the 
complexly arranged and tough skeleton; on the other hand diffi- 
eulty in securing a selective stain of the nerves in an animal whose 
nerves are non-medullated and run through dense connective tissue 
or muscle at many critical points. After several unsuccessful trials 
with material not suitably fixed or too brittle, a series of sections 
10 «u in thiekness was obtained, which is complete and perfect, ex- 
cept for a small break in the median wall of one auditory capsule 
through six or eight sections, which fortunately did no harm. The 
material was hardened in ZENKERS fluid and the fixation was good 
throughout, although not quite so good in the brain as elsewhere. 
The sections were fixed to the slide by the albumin-water method 
and stained as follows. The sections were placed in alum carmine 
for several hours until the nuclei were well stained. After rinsing 
they were brought into a mixture of saturated nigrosin, saturated 
pierie acid and one per cent. acid fuchsin in water in proportions 
arrived at by trial. In the proportions used, the nigrosin attacked 
the nervous system throughout, staining it a slaty blue-gray; the 
pierice acid stained the muscle, the cells of sense organs, the carti- 
lage, and the blood corpuscles; the acid fuchsin stained the fibrous 
connective tissue of various organs with different intensity. The 
nigrosin staining of the nervous system was excellent both centrally 
and peripherally, and the value of the combination stain can be 
illustrated by this fact. In all the haematoxylin preparations with 
or without a contrast stain which I tried, so important a nerve as 
the buccal is utterly lost for a distance of thirty or more sections 
where it passes from its ganglion. forward around the trigeminus 
sanglion laterally. It runs through a dense mass of connective tissue 
which stains in haematoxylin of the same tone as the nerve and 
more deeply. In the preparations here described the nerve stands 
out boldly of a slaty blue in the midst of red fibrous tissue. . 
The haematoxylin and GoL6ı sections formerly used for the 
study of the brain have been reviewed and compared with the pre- 
sent preparations and various incomplete series or series stained by 
methods unsatisfactory for the main purpose, have thrown light on 
special points. Unless otherwise stated, the description and figures 
refer to the one series of sections. 
The reconstruction given on plate V was first made on paper 
ruled in squares, on the scale of ten sections to the square. It has 
since been reduced by the lithographer without change of the scale, 
