418 
APPENDIX. 
The study of the brain is best made on properly hardened 
specimens. These may be prepared as follows: Remove the 
head from the body, and cut away enough of the roof of the 
skull freely to expose the brain; then put the skull with the 
contained brain in a bowl and cover with a saturated, watery so¬ 
lution of chloride of zinc. Leave the brain (fowl or rabbit) in 
: this solution from five to seven days; then replace the zinc solu¬ 
tion with fifty per cent, alcohol for twenty-four hours, then 
with sixty, seventy, and eighty per cent, alcohol each for the 
same length of time. The brain will then be sufficiently hard¬ 
ened to bear careful handling without injury, and may be re¬ 
moved from the skull (Fig. 141). The brain may be cut into 
longitudinal and transverse sections about an eighth to a quar¬ 
ter of an inch thick, to show the internal structure. 
As the representative of the mammals, a rabbit or a cat may 
be used. The order of study is quite the same as that given 
for the bird, viz.: Examine first the general external features, as 
shape, integument, limbs, head, etc.; then remove the skin and 
study the underlying muscles; after which open the body and 
examine the digestive, respiratory, and circulatory systems, and 
the more superficial parts of the nervous system. Open the 
skull, and study the brain and its coverings. Use should, as be¬ 
fore, be made of the appropriate figures, of which there are 
many, illustrating the structure of mammals. 
