Harriet Randolph.

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which the intestine is attached to the
dorsal body-wall.

(/) The bladder : a thin-walled bilobed sac
in the posterior ventral part of the
Insert a bloivpipe into the glottis and inflate.

The lungs, if hidden before, will now come

into view.

Pass a probe into the mouth and through the

oesophagus into the stomach. Turn the liver

forward to see the oesophagus and stomach.

Uncoil the intestine and identify its parts.

Find :

(g) The pancreas, in the loop between the

stomach and duodenum.
(h) The spleen, in the mesentery near the

beginning of the large intestine.
(i) The two lobes of the liver. Observe that
the larger lobe is subdivided into two.
Note the position of the gall-bladder.
Make a slight slit in the duodenum and
try by pressing upon the gall-bladder


to make the bile pass to the duodenum.
Look now for the bile-duct.
(/) The fat bodies : long slender yellow masses
on each side, attached to the dorsal
wall of the body-cavity at about the
level of the posterior border of the liver.
In different specimens they vary much
in size.
Identify :

(k) The reproductive organs.
IY. The Circulatory Organs.

Open the per icar dial cavity, using great care not
to injure the anterior abdominal vein which
passes dorsally in the posterior wall of the

1. Examine and sketch the heart, showing its
parts :

(a) The auricles : dark colored and with thin


(b) The ventricle : of paler color and conical.

(c) The truncus arteriosus: arising from the

anterior side of the ventricle, passing
obliquely forward and dividing into two
large branches.

Turn the apex of the heart forward and note
on its dorsal side :

(d) A darker triangular-shaped region, the

sinus venosus. It is closely related to the
auricles, and receives the great veins.

FROG. 101

2. Observe the contractions of the heart. Note

the order of sequence of the contraction
in the four parts of the heart. The heart of
lower vertebrates often continues to beat
after the death of the animal.

3. The veins.

A. The Anterior Abdominal Vein and its Trib-


(a) Trace the course of the anterior abdominal

vein into the liver. Just before its en-
trance it divides into two branches, one
going to each main lobe of the liver.

(b) Trace it posteriorly. It is formed by the

union of two pelvic veins which are
ventral branches of the femoral veins.

(c) Trace the pelvic vein of one side back to

the femoral from which it arises.

(d) Follow the femoral vein posteriorly, to

see from what region it is bringing

B. The Kenal Portal System.

(a) The dorsal branch of the femoral vein is
the renal portal vein. It receives the
sciatic vein and small veins from the
body-wall, etc. The renal portal vein
passes forward to the outer side of the
kidney and enters that organ by means
of numerous branches.

C. The Hepatic Portal System.


(a) Raise the liver and find the vein that
enters its left lobe, the hepatic portal
vein. Trace it posteriorly and find the
veins that unite to form it :
(act) The gastric vein : from the stomach.
(bb) The intestinal veins.
(cc) The splenic vein.

The hepatic portal vein just before entering the
liver gives off a branch that anastomoses with
the anterior abdominal vein.
D. Yeins Opening into the Sinus Venosus.

(a) The inferior vena cava: a median vein

which opens into the posterior part of
the sinus venosus. It brings blood to
the heart from the liver and kidneys,
etc., and from the hind limbs. It is
made up by :

(aa) The renal veins : from the kidneys.
(bb) The genital veins,
(cc) The right and left hepatic veins from
the liver. These open into the
vena cava inferior close to the sinus

(b) The right superior vena cava. It brings

back blood from the right side of the
head and body and from the right fore-
limb. It is formed by :
(aa) The external jugular vein : formed by:

FROG. 103

(aaa) The lingual vein : from the

(bbb) The inferior maxillary vein : from

the lower jaw.
(bb) The innominate vein : formed by

(aaa) The internal jugular vein : from

the brain, etc.
(bbb) The subscapular vein : from the

muscles of the shoulder.
(cc) The subclavian vein : formed by

(aaa) The brachial vein : from the fore-
(bbb) The musculo - cutaneous vein

from the skin, etc.

(c) The left superior cava : similar to the right.
E. Yein Opening into the Left Auricle,
(a) The pulmonary vein : formed by" the union
of the right and left pulmonary veins.
Each pulmonary vein runs along the
inner side of its lung.
Diagram of the veins !
4. The Arteries.

Distend the oesophagus by inserting the rubber
top of a pipette or a roll of paper, and thus
stretch the arteries.

Note the division of the truncus arteriosus
into two branches, and that each of these
is subdivided into three aortic arches :


(a) The anterior or carotid arch. Its chief

branches are :

(aa) The lingual artery : to the tongue.
(bb) The carotid artery : to the brain, etc.

(b) The middle or aortic arch. It runs around

the throat to the vertebral column and
unites with its fellow to form the dorsal
aorta. It gives off on each side at the
level of the arm :
(aa) The subclavian artery : to shoulder

and fore-limb.

(bb) The vertebral artery : to the vertebral
column and back, etc.

(c) The third, posterior, or pulmonary arch:

to the lung on each side. On the way
it gives off:

(aa) The cutaneous artery : to the skin,

(d) The dorsal aorta and its branches.
Posterior to the union of the two aortic

arches the dorsal aorta lies in the
median line just ventral to the vertebral
column. It gives off the following
branches :

(aa) The coeliaco-mesenteric artery : a me-
dian artery to the stomach and
intestine. Its branches are :
(aaa) The ereliac artery: to the
stomach and to the liver.

FROG. 105

(bbb) The mesenteric artery : to the

intestine and to the spleen.
(bb) The renal arteries : to the kidneys.
(cc The genital arteries : to the reproduc-
tive organs.

(dd) The inferior mesenteric artery: sup-
plying the base of the large intes-

(ee) The common iliac arteries : formed by
the division of the dorsal aorta.
Each continues down the leg as
the sciatic artery after having
given off:
(aad) The hypogastric artery : to the


Diagram of the Arterial System !
T. The Urino-genital Organs.

Remove the alimentary canal between the base of
the oesophagus and the posterior third of the
large intestine.
Posterior to the fat bodies are the reproductive

In the female :

1. The ovaries : lobed organs, varying much in

size with the season of the year.

2. The oviducts : convoluted tubes, one on each

side. The anterior end is funnel-like, and
the tub.e passes posteriorly to open into the


3. The kidneys : elongated red masses close to

the vertebral column.

4. The adrenal bodies : a band of yellow tissue on

the ventral side of each kidney.

5. The ureters : two whitish tubes passing from

the outer edge of the kidney to the cloaca
In the male :

1. The testes : a pair of yellowish rounded


2. The genital ducts (vasa efferentia) placing

each testis in communication with the
kidney of the same side. In the male the
ureter serves also as a genital duct.

3. The kidneys, as in the female (see above).

4. The adrenal bodies, as in the female (see


5. The ureters, as in the female (see above).
Diagram of the Reproductive Organs !

VI. The Nervous System.

A. The Central Nervous System.
Cut the skin along the median dorsal line and
turn it back. Remove the muscles from the
vertebrae. Open the neural canal by cutting
the membrane between the skull and the first
vertebra. Remove the roof of the brain-cavity
gradually, bit by bit, with small strong for-
ceps or with small strong scissors. In the
same way remove the neural arches of the

FROG. 107

Note the delicate pigmented membranes that
cover the brain and the spinal cord. The
outer, the dura mater, is often more or less
torn in removing the bone. The inner, the
pia mater, lies very close upon the nervous
tissue. It is usually more pigmented than
the dura mater.

Before the brain can be removed for further
investigation it must be hardened by ex-
posure to formic aldehyde.
To remove the brain :

Cut through the olfactory tracts (or nerves) close
to the nasal pits lift the anterior end of the
brain gently , cut through the cranial nerves
close to the skull and through the spinal
nerves. Take out the brain and spinal cord
and put into a small dish of water (or dilute

Sketch the nervous system thus exposed :
1. The brain : the dorsal aspect (from before
backward) :

(a) The olfactory lobes, each passing anteriorly

into a cylindrical portion : the olfactory

(b) The cerebral hemispheres, separated from

each other by a deep cleft. They are
marked off from the olfactory lobes by
a slight transverse depression.

(c) The thalamencephalon: immediately behind


the cerebral hemispheres. In the middle
line between the diverging ends of the
cerebral hemispheres the pineal gland
is borne.

(d) The optic lobes: two conspicuous rounded

bodies, one on each side.

(e) The cerebellum: a narrow ridge posterior

to the optic lobes.

(/) The medulla oblongata: the region posterior
to the cerebellum, broadest at the an-
terior end and passing gradually into
the spinal cord. Its dorsal wall is a
thin, highly vascular membrane, the
choroid plexus of the fourth ventricle.
Beneath the choroid plexus is the cav-
ity of the fourth ventricle.

2. The Spinal Cord : continued posteriorly from

the medulla oblongata. It is flattened
dorso-ventrally. Near the region of the
sixth vertebra it tapers rapidly to a slender
thread, the filum terminale. The filurn ter-
minale and the proximal ends of the lumbar
nerves form the cauda equina. Note in the
median line a slight groove not well marked
throughout, the dorsal fissure.
Turn the brain and spinal cord ventral side upper-
most, and sketch. Note :

3. The Brain :

(a) The olfactory lobes and nerves.

FROG. 109

(b) The cerebral hemispheres.

(c) The optic chiasma : ventral to the posterior

end of the hemispheres. Trace the
bundles of fibres as far as possible.

(d) The tuber cinereum : a shield-shaped body

posterior to the optic chiasma. On its
posterior border attached by a slender
stalk :

(e) The pituitary body.

(/*) On each side of the pituitary body the
crura cerebri : two columns of fibres con-
necting the cord and the medulla with
the anterior part of the brain.

4. The Spinal Cord, continued posteriorly from

the medulla. Note the median (ventral)
fissure throughout its length.

5. The Cavities of the Brain.

With a razor make a horizontal cut midway
between the dorsal and the ventral sides to
show :

(a) In the cerebral hemisphere on each side

the lateral ventricle.

(b) Connecting the two lateral ventricles the

foramen of Monro.

(c) In the optic lobes the ventricles of the

optic lobes.

(d) Connecting (a) and (c) the third ventricle.

(e) In the medulla the fourth ventricle.
B. The Sympathetic Nervous System.


Lay the frog ventral side up and carefully re-
move ike digestive, excretory, and reproductive
Observe :
1. Along the vertebral column on each side and

close to the dorsal aorta a slender cord.
With great care raise it slightly and note :
The yellowish enlargements along its length,

the sympathetic ganglia.
Count the ganglia, being careful not to injure


C. The Peripheral Nervous System.
1. Spinal Nerves : passing out from between the

vertebrae. Count those of one side.
Gently raise the sympathetic cord, and note
the branch from each spinal nerve to a
sympathetic ganglion.

Note the grouping of the spinal nerves into
plexuses :

(a) The sciatic plexus; formed from the 7th,

8th, and 9th spinal nerves. From the
plexus the sciatic nerve is given off.
Trace this into the leg.

(b) The brachial plexus : formed from the 2d

and 3d spinal nerves. It gives rise to
the brachial nerve. Trace this nerve
into the arm.

Between these two plexuses the 4th, 5th, and
6th spinal nerves pass out separately as


small nerves to the muscles and skin of
the body -wall.

Diagram of the sympathetic ganglia and their
principal nerves, and of the spinal nerves
of one side.

VII. The Eye.

With fine scissors make an incision in the skin
above the eyeball. Continue this cut around
the edge of the socket. Lifting the eyeball
by the edge of the skin, cut it free from the
muscles and nerve beneath. Take out both
eyes and harden them for two or three days
in formic aldehyde solution.
Divide one eye into right and left halves,

and one into proximal and distal halves.
Observe :

1. The sclera. 4. The retina.

2. The cornea. 5., The lens.

3. The choroid coat. 6. The vitreous humor.

VIII. Muscles.

Cut through the skin around the junction of
the leg with the body, and strip the skin
from the leg.

Bend the leg, and try to distinguish the
flexors and extensors. Dissect the leg
to show the sartorius and gastrocnemius
muscles. (See diagram.)*

* Enlarged from Figs. 80 and 81, Ecker's "Anatomy of the
Frog," translated by G. Haslam. Clarendon Press, 1889.


How does a muscle begin and how does it

end? Compare the middle with the end.
IX. Bones.

Examine the articulation of the femur with

the pelvis. Observe the end of the bone,

cartilage, etc.
Clean up the knee-joint, the pelvis, one or

two vertebrae, and the skull, and see their



I. External Characters.

1. Make an outline sketch showing the fins,

orifices, etc.

2. Find the operculum. Lift it up and find :

3. The gills. How many are there? How many

slits between the gills (gill-clefts) ?

II. Abdominal Viscera.

Cut through the body-ivall on loth sides along the
lines indicated in the diagram.* Remove the
portion of body -wall thus cut out.
Observe :

1. The liver, a conspicuous brownish lobed organ.

Lift it up to see :

2. The gall-bladder.

3. The hepatic veins, passing anteriorly from

the liver.

4. The stomach, partly concealed by the liver.

5. The intestine, passing posteriorly from the

stomach with one or two turns to the anus.

* An outline-diagram of the fish with lines to mark places for
cutting :

1. Antero-posteriorly : parallel and slightly ventral to the lateral


2. Dorso-ventrally from the median ventral line to meet the

first cut:

(a) An inch in front of the anus.

(6) Obliquely just posterior to the pectoral and pelvic



6. The pyloric appendages, finger-like organs

opening into the alimentary canal at the
junction of stomach and intestine.

7. The spleen, a dark red body lying in one of

the loops of the intestine.

8. The reproductive organs.

9. The air-bladder.
Diagram !

Cut through the intestine an inch from the anus
and through the hepatic veins close to the liver,
and remove all the organs thus far seen except
the air-bladder.

Cut through the air-bladder (noting the rete
mirabile on its ventral ivall) to see :

10. The kidneys, elongated red organs pressed

close to the dorsal wall of the abdominal
cavity, one on each side of the vertebral
column. Put a bristle into the outer open-
ing of the ureter and trace it to the kid-

11. The genital duct.

Diagram of the kidneys and reproductive organs.
III. Circulatory System.

Dissect away the left half of the pelvic and pec-
toral girdles from below upward, not injuring
the veins.
Observe :

FISH. 115

1. The pericardial cavity and the septum sep-

arating it from the abdominal cavity.

2. The heart .

(a) The sinus.

(b) The auricle.

(c) The ventricle.

(d) The bulbus (conus).

3. Find the veins coming to the heart :

(a) The hepatic veins, passing through the
septum from the abdominal cavity and
opening into the sinus.

(6) The pre-caval veins (ducts of Cuvier), one
on each side formed by the union of
the jugular vein from the anterior and
of the cardinal vein from the posterior
region, passing ventrally along the sep-
tum and opening into the sinus.

4. Trace the ventral aorta from the bulbus and

find its branches.

5. Find the dorsal aorta (dorsal to the air-blad-

der) and trace it forward into the ceph-
alic circle.

Diagram of the veins and arteries.
IV. Exoskeleton.

Take off several scales from different parts
of the body. Examine with a low


I. External Characters.

1. Note the shape of the head, the neck, the

trunk, and the tail.

2. Note the arrangement of feathers in the body,

the wing, and the tail. Pull out some of
each of the different kinds and keep them
for examination.

3. Sketch the head. How many openings ? Com-

pare with those of the frog.

4. Observe the different parts of the wing and

of the leg. Find the hand and the foot.
Note the attachment of the feathers. "What
forms the covering of the foot ?

5. Pluck.

(This can be done more easily if the skin of the
bird is first thoroughly wet with very hot
water. Great care should be taken when
pulling out feathers from the neck not to
tear the skin of that region.)

II. The Abdominal Yiscera.

Make a median longitudinal cut through the
skin on the ventral surface of the body and
neck, being careful not to cut deeper.

Turn back the skin, and keeping it moist, note :

1. The oesophagus and crop.

2. The trachea.


PIGEON. 117 -

3. The blood-vessels (be careful not to injure


Slit the trachea transversely in the middle neck-
region and ligature the neck through the slit
and under (i.e., not including) the skin. Cut
.off the head above the ligature. Open the
brain-cavity by shaving off the bone, exposing
cerebrum and cerebellum, and put the head at
once into formic aldehyde solution (as for
frog's brain).

JtfaJce a transverse cut through the body-wall
of the abdomen posterior to the pectoral

4. Note the air-sacs. How many are visible ?

5. Observe the intestine and the fat in the mes-


6. Find the falciform ligament, a thin membrane

with a large vein, in the median vertical

plane and attached to the middle line of

the sternum beneath the keel.
7. Insert a tube into the trachea and bloiv up the

structures connected with it. (Compare II.

4., above.)

Holding the sternum with the right hand press
gently with the left thumb upon the part of
the crop that lies against the pectoral muscles
and thus separate the crop from the anterior
border of the sternum.
Note beneath the crop :


8. A bilobed sac in the angle formed by the

furcula, the interclavicular air-sac.

9. Dorsal to each lobe of the interclavicular

air-sac is one of the paired prebronchial air-

Cut through the left pectoralis major muscle dose to
the keel of the sternum along its whole lengthy half
an inch deep at the anterior end and less deep as
the posterior end is approached. From the
anterior end continue the cut laterally and
dorsally to separate the pectoralis major from
the furcula. From the posterior end of the
keel continue the cut laterally to separate the
muscle from the body of the sternum. With
the handle of a scalpel gently separate the
pectoralis major from the pectoralis minor be-

10. The pectoral blood-vessels.

11. The axillary air-sac.

12. Note the oesophagus passing posteriorly from

the crop.

Cut carefully through the remaining muscle (pec-
toralis secundus) close to the keel of the sternum.
With strong scissors cut through the body of
the sternum close to the keel cut through the
furcula and cut away the articulation of the
coracoid with the sternum.


Reflect the two sides of the body-wall and
note the viscera now exposed to view :

13. The heart in the pericardium.

14. The liver. How many ]obes has it ? Which

one is larger ?

15. The duodenum, a U-shaped loop of the


16. The pancreas, lying between the limbs of the

loop. Look for its ducts.

17. The gizzard.

18. The loops of the small intestine.

19. The epigastric vein, carrying blood from the

omentum and passing up in the falciform
ligament to the anterior border of the

(Note : 20 and 21 should be left until after

20. Unravel the intestine and observe :
(Esophagus. Intestine.

Crop. Rectum and rectal coeca.

Proventriculus. Liver.
Gizzard . Pancreas.

Diagram of the abdominal viscera, ducts, etc. !

21. Cut open the gizzard and observe its struc-

III. The Circulatory System.

The Heart.
Open the pericardium and observe the heart :


Diagram !
The Veins.

A. The anterior venae cavae, one on each side open-

ing into the right auricle ; formed by the
union of :

1. The jugular vein, bringing back blood from

the head and neck, receiving :
(a) The vertebral vein.

2. The brachial vein, bringing blood from the


3. The pectoral vein, bringing blood from the

chest muscles.

B. The posterior vena cava, an unpaired vein, open-

ing into the right auricle; formed by :
1. The two iliac veins. Each iliac vein begins
near the anterior end of the kidney by the
union of :

(a) The femoral vein, bringing blood from the


(b) The hypogastric vein, passing through the

kidney and formed in the posterior
abdominal region by the union of :

(oa) The caudal vein, an unpaired vein
from the tail.

(bb) The internal iliac vein from the pelvis.

(cc) The posterior mesenteric vein (coccygeo


mesenteric), an unpaired vein from
the lower part of the intestine.
(dd) The sciatic vein, from the leg ; open-
ing into the hypogastric vein near
the junction of the middle and pos-
terior lobes of the kidney,
(c) The renal veins, bringing blood from the
kidneys, a larger vein from the pos
terior lobes, and a smaller vein from
the anterior lobe.

2. The hepatic veins from the liver ; they join
the post cava near its entrance into the
right auricle.
O. The hepatic portal system.

1. The gastric veins, two small veins from the

left side of the gizzard to the left lobe of
the liver.

2. The portal vein, sending a branch into the

right and a branch into the left lobe of the
liver, formed by :

(a) The gastro-duodenal vein from the right

side of the gizzard, duodenum, pancreas,

(b) The anterior mesenteric vein, from most of

the small intestine.

(c) The posterior mesenteric vein from the large

intestine, etc.

The portal vein receives blood through a small
vein from the spleen.


D. The pulmonary veins, short veins from the lungs

which unite and open into the left auricle.
Diagram of the veins !
The Arteries.

A. One aortic arch, the aorta, which passes to the
right. It gives off:

1. The innominate arteries, one on each side,

giving rise to :

(a) The common carotid artery, to the head.

(b) The subclavian artery, which divides to

form :

(ad) The brachial artery, to the wing.
(bb) The pectoral artery, to the muscles of
the chest.

2. The dorsal aorta, which passes posteriorly

dorsal to the heart.
It gives off :

(a) The coeliac artery, unpaired, to the pro-

ventriculus, gizzard, spleen, pancreas,
duodenum, etc.

(b) The anterior mesenteric artery, unpaired,

to the rest of the small intestine.

(c) The anterior renal arteries, paired.

(d) The femoral arteries, paired.

(e) The sciatic arteries, paired. The sciatic

artery of each side gives off :
(aa) The middle and posterior renal arteries.
(/) The posterior mesenteric artery, unpaired,
to the large intestine.


(g) The internal iliacs, paired, to the pelvis.
(h) The caudal artery, the posterior continua-
tion of the dorsal aorta.
B. The pulmonary artries, to the lungs.

Diagram of the arteries !
N. B. Keturn here to II. 17 and 18.

IV. The Excretory and Eeproductive Organs.

Carefully remove the digestive organs, cu^ng
through the intestine about an inch from its
posterior end.

1. The ovaries and oviducts, or testes and

vasa deferentia.

2. The kidneys, adrenal bodies, ureters.

3. The cloaca.

Slit open the rectum on the ventral side and
continue the cut into the cloaca.

(a) Note the number of chambers into

which the cloaca is divided.

(b) Find the openings of the ureters on

the dorsal side of the cloaca in the

1 2 3 5 7 8

Online LibraryHarriet RandolphLaboratory directions in general biology → online text (page 5 of 8)