~~ 
Answers to Queries. 133 
removed. This being done, disarticulate the lower jaw, and cut 
off the head, placing the latter in Miuller’s fluid for 3 or 4 days, 
when it should be transferred to chromic acid and spirit mixture 
for the same length of time. 
The next step is to decalcify the bones, and to do this the 
specimen should be subjected to the action of chromic acid and 
nitric acid mixture until the bones are soft and flexible, when 
sections of the entire nasal chamber may be made in a freezing 
microtome in the usual way. The sections may be doubly stained 
with logwood and iodine green and mounted in dammar. The 
head of a Frog or Newt may, with advantage, be treated in a 
similar manner. 
The above methods are those recommended by Stirling in his 
“ Practical Histology,” and I think H. A. Parker will find them good 
and reliable. F. R. Row ey, Leicester. 
353.—Ear, Human.—This is a very difficult organ to prepare ; 
a properly-prepared cochlea yields very few good sections. The 
semi-circular canals are best obtained from a skate, whose cartila- 
ginous cranium should be cut away until the canals, with their 
saccule and utricle, are exposed. The canals are hardened in 
chromic acid and spirit-mixture for a week, then transferred to 
spirit. The ampulle receive nerves, and may be hardened in 
osmic acid. Sections of these canals must be made with a freez- 
ing microtome after steeping in syrup and gum. For the cochlea, 
kill a guinea-pig and disarticulate the lower jaw, when the osseous 
tympanic bulla is exposed. ‘This lies just behind the fossa for the 
condyle of the lower jaw. Cut away the external auditory meatus, 
remove petrous portion of the temporal bone with the bulla from 
other skull-bones. Open the bulla with bone forceps, when a 
conical elevation—the cochlea—is seen. Remove all the sur- 
rounding bone and isolate the cochlea. Place at once in Muller’s 
fluid for a fortnight. Then transfer to chromic and nitric acid or 
a solution of picric acid. Shake the fluid from time to time to 
facilitate the softening. After this preserve, first, in weak and 
then transfer to strong spirit. To make sections, first steep in 
water, to get rid of the spirit, and then it is subjected to the syrup 
and gum process. Make sections parallel with the mediolus—z.e., 
across the turns of the cochlea, in a freezing microtome. Great 
care must be used, and stain in logwood or picro-carmine, and 
mount in glycerine. If a human cochlea, obtain fresh as possible. 
Cut out part of the temporal bone containing the cochlea. Split 
up in the axis of the meatus auditorius intermis ; this gives two 
pieces of bone, one containing the cochlea and a part of the 
vestibule, the other the semi-circular canals and part of the vesti- 
bule. Place at once in Miiller’s fluid (3 parts) and spirit (1 part) 
for three weeks. Transfer them to a } per cent. solution of 
