PRACTICAL DIRECTIONS. 463 
already been done. (Ifa fresh specimen is used, and the head is to 
be employed for other purposes, the brain can be removed without 
separating the head from the body, and without taking away the 
lower jaw and other structures on the ventral surface of the skull.) 
Have at hand dissecting-instruments and a dish containing 
alcohol and formalin in the following proportions (Parker and 
Floyd’s mixture): 
g5 per cent. alcohol....... .......... 6 parts 
2 per cent. formalin................. 2 parts 
In the bottom of the dish should be placed a little absorbent 
cotton, to support the brain. 
In removing the brain have at hand entire and dissected skulls 
and note the relations of parts on these as far as necessary before 
cutting the specimen. 
With bone-forceps make a small opening in the parietal bone so 
as to expose the dura mater, but do not cut through the dura mater. 
With some blunt instrument free the dura mater from the bone about 
the opening, and continue to cut away the bone until the dorsal and 
lateral faces of the cerebrum are fully exposed craniad of the 
tentorium. The olfactory bulbs (Fig. 137, 7) should be exposed 
carefully and as fully as possible. Cut away the dorsal arch of the 
atlas and carefully insert the forceps in the foramen magnum and, 
working as before, remove the squamous portion of the occipital and 
the parietal bones as far as the tentorium and as far ventrad as 
possible. Leave the dura mater intact if possible. Free the surface 
of the tentorium from the dura mater, carefully separate slightly the 
cerebellum and cerebrum; insert the bone-forceps (not too far) with 
the blades inclined from without ventromediad, and cut the tentorium 
on each side. Remove it slowly, cutting adhesions to the dura 
mater. That part of the dura mater which dips between the cerebral 
hemispheres is the falx cerebri. Cut the dura mater along both sides 
of the falx cerebri and remove it by turning it down at the sides and 
cutting it at the level of the cut edge of the bone. Remove it also 
from the cerebellum and notice how it dips down on both sides of 
the tentorium and in close contact with it. Cut the falx at the 
cranial end between the olfactory bulbs and cut the tentorial dura 
(cut its adhesions, but do not remove with it the pineal body). The 
falx and tentorial dura may then be removed. 
Allow the head to hang sideways over the dish of alcohol-formalin 
in such a way that the brain will tend to fall out of the cranium. 
Free the olfactory bulbs from the bone. Then begin at the caudal 
end and tilt the brain out with the handle of a scalpel. In doing 
this note carefully and cut the cranial nerves. They should be left 
with central ends as long as possible, and those on the side which is 
uppermost should be cut first. In doing this refer to the foramina 
in the base of the skull and to Fig. 138. Take especial pains also 
not to break off the hypophysis, which is lodged in the sella turcica, 
