Page 206 - Biology_F5

Comparative studies of natural groups of organisms

Cut the skin forward to the level of (j) Lift the abdominal vein by using
the lower jaw; cut transversely at the forceps and cut alongside it to the
level of each arm as far as the elbows. breast bone (xiphisternum). Then,
Similarly cut the skin back to the level hold the loose piece of the abdominal
of the pelvic girdle and cut towards wall up and cut across the centre of
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the side of each hind limb down to the the xiphisternum. Grip the cut piece,
knee. loosen it as far as the ligatured part and

(h) Hold the skin with forceps and loosen cut it close to that part; be careful not
the skin from the underlying muscles to cut the vein.
using the surgical blade, turn the skin (k) Cut through the pectoral girdle on
flap back and pin it. either side of the mid-line and remove

(i) Ligature the ventral abdominal vein at the central piece of the girdle to expose
two sides. Use scissors to make two the heart, and then cut the body wall
transversely below the arms.
small slits and insert a loop of thread
through the slits by using forceps and (l) Turn the tray in such a way that the legs
grip between their points; pull the are facing away from you, cut the body
thread through the slits and cut the wall on either side of the mid-line to
loop, and then tie the threads apart the pelvic area, remove the portion of
in order to prevent bleeding and cut the body wall and cut transversely to
between the ligatured points (Figure each leg. Pin aside the body wall and
3.68). turn the tray to its original position.
At this point the body cavity will be
already opened up.

(m) Remove any debris and leave the
dissection clean.

Sting (n) Cover the dissection completely with
water to avoid the drying of the organs
and enhance clear observation.

A hole (o) With the help of a hand lens, observe
ligature
the visceral (general) view of the
dissected frog and note the position
and shape of the organs (Figure 3.69).

Figure 3.68: Ligaturing of the a frog

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