The bones will of course be studied from dried specimens. These may be
prepared once for all and kept in the laboratory from year to year. A
number of mounted skeletons of the cat should be at hand; these must be
prepared by some one who has skill in such work.
_Preparation of Separate Bones._--For preparing the separate bones the
liquid-soap process recommended by Wilder and Gage (“Anatomical
Technology,” p. 107) will be found most convenient. This is as follows:
The skin and soft parts are removed as far as possible without injury to
the bones.
Make the following “liquid-soap” mixture:
Soft water 2000 cc.
Strong ammonia 150 cc.
Nitrate of potash (saltpetre) 12 grams.
Hard soap 75 grams.
Heat these together till a homogeneous mixture is formed. Now immerse
the bone or bones to be cleaned in a liquid composed of four parts water
to one part of the above liquid-soap mixture. Boil forty minutes; pour
off the liquid and renew it. Boil about half an hour longer; then remove
soft parts with fingers, scalpel, and brush. The bones may be boiled as
much longer in the mixture as is necessary to make the soft parts come
away easily. If they are boiled too long, however, the epiphyses will
separate from the bones. This is especially likely to occur in young
skeletons, which must therefore not be boiled so long as the bones of an
old cat.
Skeletons prepared in the following rough way are useful for many
purposes. The entire body of the cat, or a single limb, is placed in the
liquid-soap mixture (after partial removal of soft parts), and boiled
till the muscles may be removed, but the ligaments, holding the bones
together, remain. Clean thoroughly without removing the ligaments, and
allow to dry. The bones are thus held together in their natural
positions. Skeletons so prepared are not elegant, but are frequently
useful.
_Disarticulation of Skulls._--The bones of the skull may be separated as
follows: Clean the skull in the liquid-soap mixture, as above described.
Then fill the cranial cavity with dry rice, beans, corn, or some other
seeds that swell much on imbibition of water. Cork up the foramen
magnum, and place the skull for twelve to twenty-four hours in water.
The swelling of the grain will partially separate the bones at the
sutures. The bones may then usually be separated completely by hand.
Entire skulls, and longitudinal sections, as represented in Fig. 43, p.
60, should be at hand.
_Study of the Bones._--The bones should be studied in the order in which
they are described. No further special directions for their study are
necessary.
_Study of Ligaments._--It will usually not be practicable for each
student to make the dissections and preparations necessary for studying
the ligaments. Rather should these be examined on demonstration
preparations preserved in the laboratory. Such preparations may most
easily be made by using _fresh_ material, and dissecting away muscles
and other tissues, leaving only the ligaments connecting the bones. The
preparations are then preserved in one or two per cent. formalin. It is
difficult to prepare the ligaments satisfactorily on preserved material,
because they do not stand out clearly from other tissues in such
material, so that they are not easily distinguishable.