Text Book of Biology, Part 1: VertebrataWells, H. G. (Herbert George)
Science
Text Book of Biology, Part 1: Vertebrata
Wells, H. G. (Herbert George)
Biology -- Textbooks
Animals for dissection may be obtained from the recognised dealers,
who usually advertise in such scientific periodicals as Nature,
Natural Science, and Knowledge. Sinel (naturalist, Jersey) is the most
satisfactory dealer in dog-fish in our experience; Bolton (Malvern) will
supply Amphioxus through the post; frogs and rabbits may be
obtained anywhere. The tame variety of rabbit is quite satisfactory for
the purpose of dissection.
The following notes may possibly be of some use to the student; they
follow the lines of work arranged by the author for the evening classes
of the University Tutorial College, classes considerably restricted as
regards time, when compared with ordinary laboratory workers. Most
of the sections below occupied about three hours, but for a student
working alone they are more likely to take four or five, and even then it
is not probable that they will be so satisfactory as if performed under
skilled supervision. There are many points extremely difficult to
convey verbally which are elucidated at once by actual demonstration
upon a specimen. Each of these dissections should be repeated, and
it is well if a different condition of the type is selected for the
repetition-- an old one if the first specimen was immature, a female if
the first was a male.
-The Rabbit_
May be killed by chloroform, or potassium cyanide, or drowned. It
may also be readily suffocated with house-hold gas. It should be killed
immediately before use, as otherwise the gastric juice attacks the
wall of the stomach, and the dissection is, in consequence, rendered
extremely disagreeable. A very young rabbit is unsatisfactory as
regards the genitalia, but otherwise there is no objection to a little
one, and it has this advantage-- that it may be immersed more
conveniently under water, in a large pie dish, for purposes of fine
dissection. The external features of the animal should be examined:
eyelids, whiskers and teeth, toes, anus, perineal space on either side
of the same, urogenital opening, and position of the ribs, vertebral
column, and limb girdles beneath the skin should be made out. Then
the animal should be pinned out through the legs, the ventral surface
uppermost, the skin opened up along the middle line from pelvic girdle
to symphyses of jaw; separated from the body wall below by means
of the handle of a scalpel, and turned back; and then the abdominal
wall should be cut into and two flaps pinned back to expose its
contents. Note the xiphisternum. The caecum and colon will be
recognised (Section 16); the stomach, the right and left central, and
left lateral lobes of the liver will probably be apparent; and the urinary
bladder (especially if distended) in the middle line behind. Without any
further dissection, but simply by turning the parts over, all the
structures of the abdomen in Figure 1, Sheet 1, will be identified.
Seek especially for and note particularly, the gall bladder, bile duct,
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