272 PREPARING THE OBONTOPHORES AND MANDIBLES FOR STUDY. 
'riie Preparation of the buccal armature is of such importance, 
not merely on account of the intrinsic interest of tlie organs them- 
selves, hut because their study sheds so much light upon other aspects 
of the science, that a brief account of the methods adopted for this 
purpose by Pi’of. (irwatkin, Mr. W. AIoss, Mr. J. W. Neville and 
other prominent microscopists will he useful. 
The mollnsk is killed by immersion in boiling water and, if a species 
of moderate size, extracted from its shell, and the head cai’efully 
opened from above, when the buccal bulb containing the jaw and 
odontophore will he disclosed ; if, however, the species be too small 
for convenient dissection in this way, the shell with the contained 
animal may he crushed between two glass slips. 
The buccal bulb of the larger species or the crushed mass of the 
more minute ones are i)laced in a watch-glass or test tube containing 
a solution of Caustic Potash, and allowed to remain therein for a day 
or two to dissolve the muscular investment. 
When greater expedition is desirable, the buccal bulb of the larger 
animals may he boiled in the i)Ota.sh solution in a test tube or watch- 
glass and the minute species upon the slide upon which they have been 
crushed, taking care in each case that the solution is not too strong. 
When the desired organs are freed from extraneous matter, wash 
well in clean water and if necessary place in a weaker potash solution 
fur a few hours; then give a final thorough washing, u.sing, if thought 
advisable, a very tine camel’s-hair brush to assist the cleansing 
process, more especially at the hinder end of the radula, but to secure 
the perfect removal of the potash, the radula may again be placed in 
imre water for some hours. 
When thoroughly clean, the jaw and odontophore are transferred 
to and immersed in a small drop of glycerine with which the prepara- 
tion will be thoroughly permeated in about half-an-hour, when they 
may he hnally transferred to a clean slip, upon which a droplet of 
glycerine has lieen placed, and the jaw and odontophore arranged in 
the desired positions under the microscope. If the odontophore does 
not spread out flat this may he due to a constricting upper 
membrane, which, with a lower non-constricting one, needs careful 
removal. If the radula is unavoidably somewhat torn in the process, 
it will be no disadvantage, as it will enable the teeth to be examined 
in various aspects, and in fact it is desirable to purposely make a 
tear ([uite across the odontophore to achieve this result. 
