736 
MU. A. SANDERS ON THE ANATOMY OF THE 
which it would be impossible to obtain an accurate idea of the histological elements, 
since the nervous tissue deteriorates with great rapidity after death. 
The method of procedure was to disable the animal by cutting through the spinal 
cord behind the pectoral fins, and as rapidly as possible after opening the cranium to 
dissect out the brain, and to place it at once in absolute alcohol, to which some 
drops of tincture of iodine had been added so as to give it the colour of pale sherry. 
This method, which was first suggested by Stieda (58) (see bibliographical list at 
p. 769 of this paper), and was adopted by him in his investigations, appears to have the 
effect of fixing tixe nervous elements at the moment of molecular death. 
The hardening fluid used was chromic acid; and the great point to be attended to 
was not to have it too strong, and to place each brain into a large quantity of liquid. 
The proportions used were one part of chromic acid to 800 parts of water, and the 
allowance for each moderate sized brain was one grain of chromic acid with its proper 
quantity of water ; by this means it was possible to make the medulla oblongata and 
the tuberosities of the brain of the same degree of hardness, so that a section could be 
cut including both parts. A stronger solution would cause the tuberosities of the 
brain to become brittle before the medulla oblongata had attained sufficient firmness 
to be cut. By this process a brain would take from ten days to a fortnight, according 
to the size, to gain the proper consistence. If it happened that it was not convenient 
to make sections when the brains were ready, they were kept in a solution of ten grains 
of potash bichromate to one ounce of water, which was occasionally changed. A short 
stay in this solution was rather an improvement, as the bundles of nerve-fibres thus 
acquired a yellowish tinge, and were not so easily coloured, so that they appeared 
more distinct. But a longer delay in this liquid rendered the brains very brittle, 
unless they were soft when first put in, and made the neuroglia become too granular, 
thus obscuring the view of the nervous arrangements and rendering it necessary to 
make thinner sections. 
The colouring matter employed was rosaniline, which gives the sections a beautiful 
blue tint, and which is decidedly better than carmine, being easier to use and showing 
the minute structure of the cells much more distinctly. Hoematoxylin also has a 
good effect. 
As confusion is often caused by applying the terms of direction used in human 
anatomy to the lower animals which habitually move in a different position, perhaps 
it would not be superfluous to remark that the terms used in this paper have reference 
to that position ; so that, instead of “ posterior,” the words “ dorsal,” “ upper,” or their 
derivatives will be used ; for “ anterior,” the words “ ventral ” or “ lower ;” “anterior ” 
or “ forward ” will mean towards the head ; “ posterior ” or “ behind ” towards the tail, 
instead of the meaning attached to them in anthropotomy. 
Macroscopic Anatomy of the Brain. 
The brain of the Teleostei when viewed from above is composed of three pairs of 
