VERTEBRATES
#A. STUDIES OF FISHES#
THE LIVING FISH
_Vertebrates adapted to Water Life_
_Materials._
Living goldfishes or other fishes in small aquaria for individual
study and a few fishes in a large aquarium where they have
considerable freedom of motion.
_Definitions._
_Trunk_, the portion of the body between the head and the tail.
_Compressed_, a term used to describe the shape of the body when it
is narrower from side to side than from dorsal to ventral surface.
When the opposite is true, the body is said to be _flattened_.
_Median fins_, the unpaired fins situated on the median line, dorsal
and ventral, including the tail or _caudal_ fin, the _dorsal_ fin,
and the _anal_ fin.
_Paired fins_, fins occurring in pairs of which the more anterior are
the _pectoral_ fins and the posterior are the _pelvic_ fins.
_Fin rays_, the framework or skeleton of the fins over which membrane
is stretched to form the fins. Fin rays are of two kinds: those
composed of _bone_ and those composed of _cartilage_.
_Lateral line_, a sense organ extending along each side of the fish
in a line indicated by tubes or perforations in the scales.
_Gills_, respiratory organs adapted for taking oxygen from the water.
_Operculum_, the flaps covering the gills on each side of the head.
_Pigment_, a substance which gives color to an object.
_Observations._
_Locomotion._
1. Watch the fishes in the large aquarium and determine which fins
are most used and how they are used (a) in swimming forward, (b) in
swimming upward and downward, (c) in maintaining balance, (d) in
remaining at rest, and (e) in guiding the movements of the fish.
2. What advantages are there to the fish (a) in the power to open
and close the dorsal and anal fins, (b) in having no neck, and
(c) in having a compressed form?
3. Enumerate the various ways by which the body of the fish is
adapted to rapid movement through the water.
_Feeding._
4. What is the food of the fishes you are studying? Feed them and
watch them eat. Why is the upper jaw often called a "lip"? What is
the shape and size of the mouth when opened in feeding? Does the fish
chew its food? Describe in detail the fishes' method of feeding.
_Respiration._
5. Identify the opercula and the gill openings. Watch the movements
of the opercula and mouth, and determine what movements are concerned
in breathing and their order. Describe in detail the circulation of
water used in breathing and how it is caused.
_Sense Organs._
6. Identify the eyes, nostrils, and lateral line. How many nostrils
are there and where located? What is the position and extent of the
lateral line?
7. Describe the location of the eyes. What is the shape of the outer
surface of the eyes? Why this shape? Can the eyes be moved, _i.e._
can they be rotated, rolled, or retracted? From what direction might
an enemy approach without being seen? How would such an enemy be
detected?
_Protection._
8. With what protective structures is the body covered? Do they
hinder the movements of the fish? What are the advantages of the
scale covering of fishes over the shell covering of grasshoppers or
crayfishes?
9. In what other ways are the fishes you are studying protected
against enemies? Since you cannot account for the red color of
goldfishes on the basis of use to the fish, then how do you account
for this bright color?
_The Body._
10. What is the symmetry of the fish? Into what regions is the body
divided?
_Summary of the study of the living fish._
Enumerate in one column the different adaptations which fit the fish
for life in water and in a second column state the special purpose of
each adaption.
The External Structure of the Fish
_Materials._
Freshly killed or preserved fish in dishes or shallow pans with
enough water to prevent drying. Simple or compound microscopes,
forceps, and a bristle.
_Directions._
Examine the fins and identify the membrane and the supporting rods,
or _rays_, of bone or cartilage. Notice how the ends of the
cartilaginous rays keep the membrane from tearing.
Investigate the scales as to their arrangement, number, and size.
Remove a small patch of scales along the lateral line to find how
they are attached, where the fish's color is situated, and how access
to the sensory organs of the line is permitted. Examine a scale under
the microscope.
Observe the eyes and identify the parts similar to those of the human
eye: lid, lash, tear-duct, cornea, iris, and pupil.
In front of and between the eyes, find the nostrils. By means of a
bristle determine whether these are connected and whether they do or
do not open into the mouth or the throat.
_Questions._
1. Make a list of the fins, classifying them according to their
structure.
2. Bearing in mind the differences in structure and consequent
action,--what can you say regarding the adaptation of the several
fins for protection? for rigidity or flexibility in locomotion?
3. State how much of the body is covered with scales, and where the
largest and the smallest ones are found.
4. How are the scales arranged with reference to each other? What
benefit is derived from this in protection? in locomotion? If you
have noticed any mucus or slime upon the body, state its use.
5. Do the scales or the skin bear the pigment? Give the color pattern
of the kind of fish used in class. How would this be useful to the
fish in its natural home?
6. Describe the structure of a scale and state how it is attached to
the skin. In what way is the lateral-line scale specialized?
7. State how, when the fish is swimming, the nostrils catch odors. By
means of a diagram, with arrows show the probable direction of the
water current through the nose.
8. State which of the structures of your eye are present in the
fish's eye, and which are missing. Could a fish weep? wink? How would
a fish sleep?
9. Inasmuch as light penetrates water but a little way, so that
objects can be distinguished only within about thirty feet, would the
fish be nearsighted or farsighted?
_Suggested drawings._
a. A side view of the entire fish, fully labeled.
b. A bony rayed and a cartilaginous rayed fin.
c. A scale, showing its minute structure.
d. A dorsal or a lateral view of the head, showing the sense organs.
The Mouth and the Gills of the Fish
_Materials._
The same materials as those used in the preceding exercise may be
used here.
_Directions._
The mouth, its structure and its action, can be seen by pulling the
upper jaw upward and forward until the mouth and the gill chambers
open fully. Examine the structure and action of the jaws, the tongue,
the throat, and the teeth on each jaw and on the roof of the mouth.
Investigate the breathing apparatus from the throat side and from the
exterior, noting the number, form, and structure of the gills, their
attachment and their protection.
The mouth may be kept open by a short splinter or a ball of paper.
The pupil should identify the following structures:--
1. _Gill_, an organ for breathing the air dissolved in water.
2. _Gill arch_, an arch of bone or cartilage supporting the gills.
3. _Gill filaments_, fringe-like structures attached to the gill
arches, forming the gills.
4. _Gill raker_, lateral projections from the gill arches.
5. _Gill-slits_, openings between the gill arches for the passage of
water.
6. _Operculum_, the flap-like covering of the gills on each side of
the head.
_Questions._
1. Compared with the size of its body, how wide can the fish open its
mouth? What do you infer as to the size of its "bite"?
2. Are the jaws rigidly affixed to the skull? Why should they be so
attached, or why not?
3. Of how many pieces is the upper jaw composed? the under jaw?
4. Where are the teeth? Judging from their form, size, and situation,
what do you think must be their use?
5. Do you think the tongue is used to assist in mastication? in
tasting? in speech? in swallowing?
6. How many gills are there, and where are they situated? How are
they attached? Which one is not free from the body throughout its
length?
7. What probably causes the color of the gill filaments? What is
there in their number and texture which fits them for their
function?
8. What is the direction of the water current through the gill
chamber? Of what use are the gill rakers?
9. How are the gills protected?
_Summary._
Write a complete account of how the fish eats and how it breathes.
_Suggested drawings._
a. A front view of the fish's face, with the mouth fully open.
b. A side view, as above.
c. A ventral view of the head, with both gill-chambers wide open and
the gills separated from each other. Indicate currents by arrows.
d. A single gill.
The Alimentary Canal and the Circulatory System of the Fish
_Materials._
Small fresh fish, shallow pans or dishes of water, forceps, and
scissors.
_Directions._
If the instructor has not opened the fish previously, this is to be
done by the student as follows: On the ventral side, insert the
scissors in the vent (in front of the anal fin) and cut straight
forward to a point between the opercula. Care must be exercised in
opening the chamber about the heart; this lies between the gill
chambers.
The various organs, so far as possible, should be carefully drawn out
and separated, in order that their structure may be distinguished.
The pupil should identify the following parts:--
1. _Body cavity_, the entire internal space, divided by a membrane,
_false diaphragm_, into a large _abdominal cavity_ and a small
chamber, _pericardial chamber_, between the gill chambers.
2. _Liver_, a large red or pink mass lying at the front end of
the abdominal cavity, and divided into two unequal lobes. The
_gall-bladder_, thin-walled and green, may be seen between these
lobes.
3. _Alimentary canal._
a. _Mouth._
b. _Esophagus_, in the fish a very short tube.
c. _Stomach_, white and muscular, beginning with a very short
esophagus and ending as a blind sac. If it is much distended,
open it to see what the fish may have eaten.
d. _Small intestine_, thin-walled, tubular, and somewhat coiled.
e. _Large intestine_, a short, thin-walled expansion at the
posterior end of the small intestine; usually less than half an
inch long.
f. _Coeca_, from two to several small pouches attached where the
small intestine leaves the stomach.
4. _Spleen_, a reddish brown _globule_ between the folds of the
intestine.
5. _Swim bladder_, an elongated chamber lying against the backbone,
partitioned off from the cavity below by a delicate membrane.
6. _Peritoneum_, the delicate, silvery membrane which lines the
abdominal cavity and enfolds the viscera. Note its spots of pigment.
7. _Pericardial chamber_, the chamber around the heart; see § 1
above.
8. _Heart._ As the fish is placed belly upward in the pan the
_ventricle_ faces you, pink, conical, and muscular. Posterior to it,
on the dorsal side, is the _auricle_, a membranous sac.
9. _Ventral aorta_, arising on the anterior surface of the ventricle
as a white muscular "cord" (really a tube) which is enlarged close to
the heart into a bulb, the _arterial bulb_. You should follow up this
aorta until you see it divide right and left to send its branches
outward into the gills, the branches being called _gill arteries_.
_Questions._
1. The fish frequently swallows its food alive. Why should the
stomach be muscular? Why is it better that the intestine does not
leave the stomach at the end opposite the esophagus?
2. Of what use can the coeca be? What structure of the human
intestine do you recall that is at all like them in form or use?
3. How many times the length of the body is the length of the
alimentary canal? Does this indicate that the fish is compelled to
eat a great deal of poor food or that its food is highly nutritious,
so that little need be taken?
4. Near which end of the fish's body is the heart? Is this the usual
or the unusual condition among animals you know about? What
advantages can you think of in this arrangement?
5. What advantages are there in having the heart in a chamber
separated from the other vital organs?
6. Of how many chambers does the heart consist? Why should at least
one of them be muscular?
7. How many times does the blood pass through the heart in making a
complete circuit of the body? Would you call this a single or a
double circulation?
8. Does the heart force the blood onward or does it draw blood into
itself, _i.e._ is the heart a force pump or is it a suction pump?
9. How is circulation made complete? If the heart is a force pump, is
its power sufficient to drive blood through artery, capillary, vein,
and into auricle, if the capillaries can stand the pressure, or is
another action concerned? If it is a suction pump, why does the blood
leave the heart?
_Suggested drawings._
a. The body cavity, with viscera undisturbed.
b. The alimentary canal extended.
c. The anterior end of the fish with the sinus held open, to show the
general situation of the parts.
d. The heart in its chamber, with the outgoing vessels as far as
dissected. Use arrows to show direction of circulation.
e. A copy of some good diagram or chart which illustrates the heart
of the fish with the connecting veins and arteries.
Fishes: A General Review and Library Exercise
1. Food and the feeding habits of young and of adult fishes.
2. The diet and habits of cod; lantern-fish; swordfish; ramora;
hagfish; angler; gar-pike; sturgeon; shark; sawfish; paddle-fish.
3. The variations, real or apparent, in the breathing habits of the
porcupine-fish; the climbing-fish; the lung-fish.
4. Peculiarities in swimming as seen in the flying-fish; the
flounder; the sea-horse.
5. Intensity of sound under water, and the corresponding structure of
the fish's ear.
6. Light and sight under water (as in 5).
7. Protection of fishes: sting-ray; torpedo; coral-fish; sturgeon;
lava-fish; swordfish; sawfish; pipefish.
8. The social instinct of fishes, and "schools."
9. The breeding habits of salmon; eel; stickle-back; sturgeon;
whitefish; shark; sea-horse; sunfish.
10. The fishing industries of the Great Lakes or of the cold oceans,
with a list of the fishes caught and their values.
11. Fish nets and traps: seine; gill-net; pound-net; trawl, French or
English; fish-wheel; fish-weir; spear; dip-net; set-line; spoon; fly.
12. The U.S. Bureau of Fisheries: its locations, its problems, and
its methods.
13. The State Fish Commission, as above.
14. Game and fish laws; their purpose and their enforcement.
15. Game fish of the fresh waters; trout, bass, pickerel, and
muskellunge.
16. Game fish of the ocean: tarpon, tuna, sea-bass, swordfish, and
bluefish.
17. Fish as food.
18. Fish diet and leprosy.
19. Fish diet and parasitic worms.
20. Fish nuisances: carp, catfish, and dogfish.
21. Commercial products of fishes, their preparation and their uses:
caviar, shagreen, cod liver oil, isinglass, and glue.
22. The geographic distribution of fishes, with means of dispersal
and restriction.
23. The faunal regions of the lake (or ocean), with characteristic
forms.
24. Fishes of ancient times; of the Devonian period.
25. The story of the early life of Louis Agassiz; of D. S. Jordan; of
C. H. Eigenmann; of Bashford Dean.
26. Goldfish: their origin; how to care for them.
27. Fashions in fish tails, old and new.
28. Development and variation in scales; fashions in scales.
29. The common orders of fishes, with examples.
Primitive Chordates
_Materials._
An acorn-tongued worm, a lancelet, a lamprey, a shark, and a perch.
If individual specimens are not available, the pupil's text-book and
charts are to be used.
_Observations._
_Acorn-tongued worm_: Notice the very simple form and structure of
the symmetrical body, the "proboscis," the collar surrounding the
neck with its simple rod of cartilage, the marks of internal gills
and gill slits extending some distance along the body, and the
presence or absence of sense organs. The acorn-tongued worm
(_Balanoglossus_) lives in the sand of the seashore and in shallow
water in temperate and tropical regions.
_Lancelet_: Observe the form of the body, of the fin, and of the
mouth; note the presence or absence of sense organs, and find out the
number of gills or gill slits. The lancelet (_Amphioxus_) is similar
in habit to the acorn-tongued worm. By day it lies buried with only
the mouth exposed, but at night it swims actively about. It is
somewhat more confined to the tropics.
_Lamprey_: Observe here also the primitive or unspecialized form of
the body, of the fin, of the jawless mouth, the number of gill slits,
and the sense organs.
_Shark_: Examine the body, noting its form and differentiation into
regions, its covering, its fins, mouth, gill slits, and sense organs.
_Perch_: If you have not already studied the bony fish, the points
suggested for the shark will be sufficient for this exercise.
In each case, find out the condition of the skeleton.
_Questions._
1. Which of these animals seem most simple in form, and which most
complex? Give a reason for your answer.
2. Give the stages which show how the fold of skin develops into
separate fins.
3. How does the number of gills and gill slits change in the series?
(Give definite numbers.) How may the reduction in the number of gills
be compensated for in the amount of surface exposed for the exchange
of gases in breathing?
4. How is protection afforded the delicate structure of the gills in
the final form?
5. Give the stages in the formation of a definite, symmetrical mouth
with jaws of equal size.
6. The presence of sense organs may be taken to indicate that there
is an organ of control, or brain. How is the development of this
organ like or unlike that of the other structures in the series?
7. For the developing brain and nervous system what protection and
support is afforded in each case?
The foregoing questions may be answered in tabular form by arranging
the names of the animals in a line and the questions in a column.
_Suggested drawings._
a. Acorn-tongued worm, × 1.
b. Lancelet, × 1.
c. Lamprey, × 1/2.
d. Shark: 1, head as far as the pectoral fins; 2, the tail.
e. Perch, as directed for shark.
#B. STUDIES OF AMPHIBIA#
#Progress from Water-living Animals to Land-living Animals#
The Living Frog or Toad
_To show how an Animal may be adapted to both Land and Water Life_
_Materials._
Living frogs in small cages or aquaria; living toads; some pungent
liquid, as ammonia.
_Observations._
_The Body._
1. Contrast the body of the frog with that of the fish as to regions,
shape, and compactness. How do you account for the differences?
_Locomotion._
2. What kinds of locomotion can a frog use? Why is it difficult for a
frog to crawl or walk? How far can a frog jump? How are swimming and
jumping accomplished? What do you think is the use of the "hump" on
the back?
3. Identify in the legs the thigh, shank, ankle, foot, toes, and web,
and in the arm, the upper arm, forearm, wrist, hand, and fingers.
State in detail the differences in structure and in position between
the fore and hind limbs. How do you account for these differences?
_Feeding._
4. Induce a frog or toad to eat by dangling food, such as a piece of
raw meat or meal worms, small earthworms, etc., before it. How does
it seize the food? What will it eat? How is the mouth adapted to
this manner of feeding?
_Respiration._
5. The frog has no diaphragm, and therefore no chest cavity; watch
very carefully the movements of the mouth, the nostrils, the throat,
and the sides of the body to determine how the problem of breathing
(how the air is gotten into and out of the lungs) without a diaphragm
is solved. Write a detailed account of the frog's method of breathing
which shall explain just how the air is forced into the lungs.
6. What would be the effect of propping open the mouth of the frog?
Why? Does the frog breathe in the usual manner while under the water?
If not, how do you explain its ability to remain under water for a
long period of time?
_Sense Organs._
7. Investigate the efficiency of the five special senses in the frog
by devising experiments to test each sense; as, for example, giving a
frog its liberty on the floor and trying to catch it again, to test
the sense of sight. Write an account of your experiments and their
results. Which of the senses is best developed? Give reasons for your
answer.
8. Compare the eye of the frog with respect to its shape, movements,
parts, and protective structures with that of the fish. In what
respects are they similar? in what respects different? Why should
they differ?
9. Where are the frogs' ears located? What do you think of the
efficiency of an eardrum situated on the surface of the body? Why?
10. The frog has certain other responses. Try turning the jar or cage
containing a frog around to face the frog in another direction. What
happens? How do you explain this response on the basis of use? What
other responses have you noticed?
_Protection._
11. Has the frog an exoskeleton? Describe the color scheme of the
frog and explain how it may be protective. Why are frogs brighter in
spring than in fall?
12. Why do frogs usually live near water? Do they ever leave the
vicinity of streams? If so, when?
_Summary._
In what ways is the frog adapted to water life? In what ways to life
on land? In what respects do toads differ from frogs?
The Frog's Mouth
_Materials._
Preserved or freshly killed frogs in dishes or shallow pans of water;
forceps and a bristle.
_Observations._
Open the frog's mouth as widely as possible and, if necessary,
insert a splinter to hold the jaws apart. Identify the following
structures:--
_Tongue._ Draw it forward until the free end extends from the mouth
and is outspread; observe its form, extent, and attachment.
_Teeth._ Find those on the jaws and on the roof of the mouth.
_Nostrils._ Push the bristle inward through a nostril to determine
its direction and extent.
_Vocal cords._ These form a hard white mass in the floor of the
mouth, well back behind the tongue.
_Glottis_, the slit inclosed between the vocal cords, opening into
the trachea.
_Esophagus_, the passage to the stomach, at the posterior end of the
mouth.
_Eustachian tubes_, small passages outward to the ears at the
junction of the upper and lower jaws.
_Questions._
1. Describe the probable action of the frog's tongue in catching a
bug.
2. What advantage can you ascribe to the peculiar mode of attachment
of the tongue?
3. Of what use is the notch in the inner end of the tongue? (Note its
position when the tongue lies at rest in the mouth.)
4. If the frog chewed its food, how would the existing structure of
the nostrils be very inconvenient?
5. Recall either the frog's habit of feeding or the structure of the
nostrils. Do you think the nostrils are of much service in smelling?
State the reason for your answer.
6. Of what use are the vocal cords and why are they so muscular?
Consider their use in sound making and also their condition during
swallowing.
7. Of what use are the teeth? Recall the form and use of the fish's
teeth.
_Suggested drawings._
a. The mouth, wide open and with tongue extended.
b. A diagram showing the path of air and of food through the frog's
mouth.
The Organs of Digestion, Absorption, and Excretion
_Materials._
Freshly killed or preserved frogs in dishes or shallow pans of water,
forceps, and, if the pupil is to do any dissecting, scissors.
_Directions and Observations._
The specimens may have been opened by the teacher, or may be
dissected by the pupil as follows:--
Placing the frog on its back, with forceps firmly grasp the skin of
the abdomen and the muscles beneath, just in front of the hind legs,
and with the scissors cut straight forward in the middle line until
the floor of the mouth is reached; this will separate the arms. Care
must be taken not to cut too deeply, but this may be avoided by
keeping the skin uplifted. Now cut sidewise in front of each hind leg
in order that the body wall may be laid aside. Under the arms the
heart will be seen; it will be studied as a part of the circulatory
system.
* * * * *
Identify the following organs:--
_Liver_, the large red or brown mass, consisting of several divisions
and lying close up under the arms.
_Bile sac_, small, green, and between the liver lobes.
_Alimentary canal._
1. _Mouth._
2. _Esophagus._
3. _Stomach_, the elongated, light-colored, firm, and muscular
portion.
4. _Small intestine_, a slender, more or less closely coiled,
tubular portion.
5. _Large intestine_, a thin-walled enlargement at the posterior
end of the canal.
6. _Duodenum._ This is a muscular portion of the small intestine
immediately following the stomach, against which it is folded.
_Pancreas_, a yellowish, pulpy mass lying in the fold between the
stomach and the duodenum.
_Spleen_, a dark red globule, usually smaller than a pea, lying
nearly free among the folds of the small intestine.
_Fat bodies_, yellow fringe-like structures, sometimes found near the
stomach.
_Kidneys_, a pair of elongated dark red organs, behind the spleen and
against the back. Note their numerous blood vessels. Possibly the
_ureters_, or urinal ducts, can be discovered and traced to their
junction with the _bladder_, a clear membranous sac in the posterior
extremity of the body cavity.
_Peritoneum_, a thin membrane lining the body cavity and attaching
the vital organs to the backbone.
_Note._--Specimens secured in late fall, winter, or early spring
may contain, if female, a large number of dark-colored eggs; or
if male, two white testes, located near the kidneys and similar
to them in form, though smaller.
_Questions._
1. Name the parts of the frog's alimentary canal.
2. Name the glands or organs which are accessory to the canal.
3. How long is the esophagus? How does the presence or absence of a
neck affect the esophagus?
4. How does the thickness of the stomach wall compare with that of
the intestine, and how do you account for the difference?
5. Measure the length of the trunk of the frog's body and that of the
outstretched alimentary canal. How many times the length of the one
is that of the other? How does this ratio compare with that of an
herbivorous animal? (The sheep's food canal is about thirty-two times
the length of its body.)
6. What is the color of the bile, as seen through the walls of the
bile sac? This color is characteristic of carnivorous animals; in
herbivorous forms it is yellow. Find its color in some omnivorous
form, as man.
7. Name the organs concerned in excretion.
8. What holds the internal organs in place, and from what are they
suspended?
9. The spleen is called a "ductless gland." Give its function, and
explain why a duct is not necessary to it.
10. Since the frog swallows its food alive and entire, what work must
the stomach do? What digestive organs would be absent from the mouth,
or else poorly developed?
11. Since the frog is carnivorous, what digestive ferments are
probably present, and what ones absent from the alimentary canal?
12. Fat bodies are largest in the fall, and are rarely found in the
spring. How can you account for this?
13. When through with the general study of the alimentary canal,
you may open the stomach by cutting it lengthwise. Describe the
character of the stomach lining as to folds and villi, stating
the advantage of each being present and the reason for the
direction of the folds. Tell how the food is propelled onward
through the alimentary canal. Give the scientific name for this
action.
_Suggested drawings._
a. The viscera (internal organs) undisturbed.
b. The alimentary canal extended.
c. The excretory system.
The Organs of Circulation and Respiration of the Frog
_Materials._
The materials used in this exercise are the same as those used in the
preceding exercise.
_Observations._
The pupil should identify the following structures:--
_Pericardium_, a membrane that surrounds the heart and, in the case
of the frog, separates the body cavity into two portions, the
_abdomen_ and the _pericardial_ chamber.
_Heart_, lying between the shoulders and in front of the false
diaphragm. It is conical in form and composed of three chambers.
_Ventricle_, the pink, conical, and muscular portion of the heart,
pointing backward and outward.
_Auricles_, right and left. These are anterior and dorsal to the
ventricle, thin, membranous, and dark-colored.
_Arterial trunk_, the single large blood vessel, usually empty of
blood, and white. Note its origin and trace it as far as possible, at
least until you see it divide to encircle the throat.
_Sinus venosus_, a large membranous sac dorsal to the heart and
connected with the right auricle.
_Lungs_, two small oblong, pink, spongy sacs, lying between and
behind the shoulders.
The pupil may also identify the following structures if a
specimen is available which has the blood vessels injected.
_Conus arteriosus_, or "arterial trunk," a large artery passing
obliquely forward from the ventricle, and dividing into three
branches on each side.
_Carotid arteries_, the first branches of the conus, to the head
and neck.
_Aortas_, the second branches of the conus, to the dorsal region.
_Pulmocutaneous arteries_, the third branches of the conus, to
the lungs and skin.
_Dorsal aorta_, the large artery along the back, formed by the
union of the two aortas.
_Iliac_, or _femoral arteries_, the two posterior divisions of
the dorsal aorta, supplying the legs.
_Posterior_ (ascending) _vena cava_, a large vein close to the
dorsal aorta, passing forward from the kidneys.
_Hepatic veins_, large veins connecting the liver with the
posterior vena cava.
_Anterior_ (descending) _venæ cavæ_, large veins formed by the
junction of the veins from the arm, neck, and head on the right
and left sides.
_Subclavian veins_, from the arms.
_Jugular veins_, from the neck.
_Questions._
1. Of how many chambers does the frog's heart consist? Name them, and
describe them as to size, color, and structure.
2. Which chamber receives blood from the body, and which receives
blood from the lungs?
3. Name the large arteries and give the regions which they supply.
Name the large veins and give the regions from which they come.
4. Describe the lungs as to size, both when inflated and when
uninflated. Describe their color; entirety or subdivision; texture.
5. In the inflated lung, notice the interior partitions or chambers,
which are called _vesicles_. How do they affect the amount of surface
exposed for gas exchange in breathing?
6. Measuring the lung collapsed and again when inflated, calculate
its approximate volume in each case and state how much air it may
take in during an inspiration.
7. Describe the diaphragm and state its probable use as a factor in
respiration or as a partition.
_Advanced questions._
8. Apparently the pure and the impure blood must commingle upon
entering the single ventricle, but by a simple device this
scarcely occurs. How would such commingling affect the purity of
the blood as it reached the tissues, and hence affect waste
removal, oxidation, body temperature, activity, and intelligence?
9. What are the chambers of the fish's heart? of the mammalian
(human) heart? How may the heart of the frog be regarded as
intermediate between these others? How and where might the growth
of a partition within it bring about the higher structure? (This
actually occurs in certain reptiles.)
10. The lungs are said to be outgrowths of the alimentary canal.
Explain how their connection would tend to show this.
_Suggested drawings._
a. The heart and lungs in their normal position.
b. The circulatory system, as seen in the injected specimen.
c. A copy of the diagram or model of the circulatory system.
d. A diagram of the respiratory tract from the nostrils to the lungs,
by arrows showing the course of the air.
The Nervous System of the Frog
_Materials._
Specimens which have the brain exposed and other specimens whose
viscera have been removed so that the spinal nerves can be seen; pans
or shallow dishes of water and forceps.
_Observations._
The nerve tissues are generally white in color unless they have been
specially treated and stained. The pupil should identify the
following structures:--
_A. Brain_, those enlargements of nerve tissue situated in the head
and composed of four principal parts, as follows:--
1. _Cerebral hemispheres_, a pair of elongated lobes, the anterior
enlargements.
2. _Mid brain_, or _optic lobes_, a pair of large ovoid structures,
projecting diagonally forward and sidewise.
3. _Cerebellum_, a slender, transverse ridge, close behind the
midbrain.
4. _Medulla_, the anterior end of the spinal cord, widest in front
and containing a triangular depression.
(Frequently a pair of smaller enlargements is to be seen in front
of the cerebral hemispheres; they are the _olfactory lobes_, and
from them nerves pass forward to the nasal chamber.)
_B. Spinal cord_, extending along the spine, giving rise to nerves.
_C. Spinal nerves_, ten pairs of nerves which are connected with the
cord through dorsal (sensory) and ventral (motor) roots, and which
penetrate the body and its appendages. The first enters the neck; the
second and third join and enter the arm; the fourth to sixth
penetrate the skin and muscles of the trunk; the seventh to ninth
join by a plexus to form the sciatic nerve which supplies the leg,
and the tenth enters the posterior portion of the body.
_Questions._
1. Which lobes of the brain are paired? Give at least two possible
causes or reasons for their double structure.
2. The optic lobes are connected with the eyes. Compare their size
with that of the other parts. Of how much use do you think they are
to the frog?
3. If folds or convolutions in the surface of the cerebrum indicate
intelligence, thoughtfulness, or mind, what do you infer as to the
frog's mental condition and power to think?
4. Has the frog brain or "brains"? Explain.
5. Name several things done by an animal's brain.
6. Which of the spinal nerves are specially large? Why should they be
large?
7. What advantages are there in the frog's having a dorsal nerve cord
instead of a ventral one, as the earthworm has?
What would be the effect of cutting or breaking the dorsal root
of a spinal nerve? the ventral root? the entire spinal cord? How
do you explain the convulsions of the brainless (beheaded)
chicken or frog?
8. What kinds of impulses originate outside of the nerve center,
and what kinds in the center?
9. Sensations reach the cord and brain through the dorsal root of
the spinal nerve. What kinds of messages travel through the
ventral root, and in what direction do they go?
_Suggested drawings._
a. The brain.
b. The spinal cord and its nerves.
c. The nervous system.
d. A diagram of the cord and its nerves, showing the kinds and the
directions of the nerve impulses.
The Endoskeleton of the Frog
_Materials._
Prepared frog skeletons mounted in glass-covered boxes or in other
cases suitable for individual study; other vertebrate skeletons for
reference.
_Observations._
The pupil should examine his specimen and identify the following
structures:--
_A. Skull:--_
1. _Cranium_, or brain case, the central and hinder portion.
2. _Nasal bone_, a triangular bone lying in front of each large
opening, or _eye orbit_, and attached to the anterior end of the
cranium.
3. _Premaxillaries_, a pair of small bones which form the tip of the
nose.
4. _Maxillary_, a slender bone forming the side of the upper jaw.
5. _Dentary_, the bone of the lower jaw, corresponding to the
maxillary.
6. _Occipital foramen_, the posterior opening or entrance into the
cranium, normally covered dorsally by cartilage and most easily seen
in a separate skull.
_B. Vertebral Column:--_
1. _Cervical vertebra_, the first vertebra, supporting the skull.
2. _Dorso-lumbar vertebræ_, vertebræ with small lateral processes.
3. _Sacrum_, the ninth vertebra, bearing extra long lateral processes
or "arms."
4. _Urostyle_, the last vertebra, lying in the median line, a long,
slender, blade-like bone, really formed by the fusion of several
vertebræ.
_C. Vertebra:--_
1. _Centrum_, the solid, nearly circular portion.
2. _Lateral process_, one of the paired projections, extending
outward on either side.
3. _Neural spine_, the single projection, extending toward the dorsal
side.
4. _Neural arch_, formed largely by a connection between the lateral
process and the neural spine. The arch above and the centrum below
inclose the _neural canal_.
_D. Pectoral, or Shoulder, Girdle:--_
1. _Sternum_, the "breastbone," extending along the median ventral
line.
2. _Coracoid_, a heavy bone extending from the sternum sidewise to
support the arm.
3. _Clavicle_, the "collar bone," a light bone in front of the
coracoid.
4. _Scapula_, the "shoulder blade," a broad, thin bone which arches
around to the dorsal side.
_E. Pelvic, or Hip, Girdle:--_
1. _Ilium_, a long, slender, curved bone, with its mate uniting to
form an inverted "wishbone"; it is joined to the sacrum.
2. _Pelvis_, the region of the socket at the junction of the ilia.
_F. Fore Leg, or Arm:--_
1. _Humerus_, the single bone of the upper arm.
2. _Radius_, the bone of the lower arm on the thumb side; in the frog
united to the ulna.
3. _Ulna_, the bone of the forearm opposite the radius.
4. _Carpals_, small bones of the wrist.
5. _Metacarpals_, a single series of long bones forming the palm of
the hand.
6. _Phalanges_, the bones of the fingers and thumb (singular
phalanx).
_G. Hind Leg:--_
1. _Femur_, the thigh bone, next to the body.
2. _Tibia_, the larger bone of the lower leg on the inner side; in
the frog united to the fibula.
3. _Fibula_, the smaller bone of the lower leg.
4. _Tarsals_, the small bones of the instep.
5. _Metatarsals_, the long bones of the instep.
6. _Phalanges_, the bones of the toes.
_Questions._
1. Whereabouts in the frog has nature made an attempt to inclose
delicate or vital structures in bony cases?
2. Examining the inside of the mouth, find the teeth. Judging from
their size and structure, of what use are these teeth?
3. What advantages can you see in having the arms and legs attached
to girdles instead of having them fastened directly to the vertebral
column? How has their development affected the shape of the trunk, as
opposed to that of the fish?
4. Make a comparison of the two girdles as to their attachment to the
spine and their consequent rigidity or freedom of movement.
5. How many vertebræ are there in the spinal column? What advantage
can you see in having the column composed of many small vertebræ
instead of a few large ones? Enumerate those having a special form or
structure, and state the use of each.
6. On the vertebræ notice any irregularities, prominences, or
roughenings. For what are such bones better adapted than smooth bones
would be?
7. How is the frog's humping permitted? How are the urostyle and the
pelvis connected, if at all? Has this any effect on motion? (See
living frog.)
8. In parallel columns, keeping corresponding parts in a line,
tabulate the bones of the fore and hind limbs.
9. State how extra length has been attained in the hind leg, and give
the purpose or the result of this lengthening.
10. In the forearm notice the fusing of the radius and ulna. How
would these parts act in rotating the hand, as compared with your
own, where they are free? Compare also the tibia and fibula. Where in
the frog's leg is turning made possible by the use of parallel bones?
11. Compare the frog's hand and foot as to number of fingers and
toes; as to length and spread. Have any fingers or toes only two
phalanges?
12. How would an inner skeleton affect the growth and the size of an
animal, as compared with an outer skeleton, like the clam's?
13. How would the lack of an outer skeleton influence sensitiveness,
activity, and intelligence?
_Suggested drawings._
a. The skull and trunk, with appendages of one side.
b. Each set of bones separately, as the skull, the column, etc.
Comparative Study of Amphibia
_Materials._
Various amphibia, either dead or alive, such as newts, mud puppies
(_necturus_), salamanders, and several species of frogs and toads,
especially tree toads.
_Observations._
Answer the following questions with respect to each animal:--
1. What regions of the body are present? What is the general shape
and size of the body?
2. For what kind of locomotion are the limbs fitted? How?
3. Have the hands and feet any special adaptations? If so, what are
they and for what purpose?
4. With what organs does the animal breathe? If with gills, are they
external or internal?
5. Judging from the specimen, what do you think is the habitat? Give
reason for your answer.
Summary from the Comparative Study of Amphibia
1. Which of the amphibia in this study are fish-like in character?
What are the fish-like characters? Do you think these fish-like
amphibia are of a lower or higher type than the others? Give reasons
for your answer.
2. Show how the variation in (a) the form of the body, (b) color
patterns, and (c) the structure of the legs and arms of the amphibia
are related to habitat and mode of life.
Amphibia: A General Review and Library Exercise
1. The usefulness of the American toad.
2. The breeding habits of the common frog; of the Surinam toad; of
the obstetrical toad; of the "smith."
3. The development of the axolotl.
4. The habits of the tree frogs and their variable coloration.
5. The croaking of frogs and of toads.
6. The flying frog of Ceylon.
7. The distribution and habits of the hellbender; of the mud puppy;
of the Congo "snake."
8. The general absence of the amphibia from arid regions.
9. Frog farming for city markets.
10. Protective devices of various amphibia.
11. Toads and warts.
12. The homing and water instincts of toads.
13. Hibernation, seasonal or prolonged, of toads and frogs.
14. The changes in the respiratory and circulatory system during
metamorphosis.
15. Ontogeny and phylogeny, as illustrated by amphibia.
16. The structural defects which would prevent an ambitious frog from
becoming a highly trained and skillful animal.
17. The classification of amphibia, with examples.
18. The kinds of frogs and toads found in the region where you live.
#C. STUDIES OF LIVING REPTILES#
#Showing Diversity of Adaptation among closely related Animals#
The Snake
1. What is the shape? What regions are present? How do you
distinguish between the trunk and the tail? Has the tail any use?
What are the advantages of a body without limbs?
2. Describe the snake's path in locomotion. How is locomotion
accomplished? Is the absence of limbs a hindrance to the animal in
its locomotory activity?
3. Describe the appearance and movements of the tongue. Of what use
are these movements of the tongue?
4. What evidence is there that the snake breathes with lungs?
5. What sense organs do you find? Compare the ears and eyes with
those of the frog. What explains the peculiar staring appearance of
the eyes?
6. What is the color scheme? Does it appear to be protective? If so,
how?
7. Of what does the exoskeleton consist? How are the scales arranged?
What variations in the size of the scales do you find? What special
use have some of the scales? How fitted for this? How does a snake
moult? Appearance before and after moulting.
The Florida Lizard
1. Describe the body as to regions and shape. Is the tail of use?
2. What are the lizard's locomotory abilities? How is it fitted for
living in trees?
3. Feed the lizard flies or meal worms and describe its method of
capturing them.
4. Compare the lizard's respiration and sense organs with those of
the snake and frog.
5. What is the usual color of the lizard? What have you discovered
about its power to change colors? How may this be of use to it?
6. Of what does the exoskeleton consist? Is the entire body covered?
How are the scales arranged? How does the lizard moult?
The Turtle
1. In what important ways does the body of the turtle differ from
those of the snake and lizard?
2. What methods of locomotion has the turtle? For which method is it
best fitted? How? Why are its movements in water so much less clumsy
than on land? (Compare weight on land with weight in water.) Compare
the efficiency of the locomotion of a turtle with that of a lizard
and suggest a reason for the difference.
3. What do turtles eat while in the laboratory? Since turtles have no
teeth, how can they bite off their food?
4. What can you discover with respect to the respiration of the
turtle? Does it breathe when under water?
5. What sense organs has a turtle? Which appears to be most highly
developed? How do you know?
6. In what various ways is the turtle protected against enemies? (You
should state several.) Are you afraid of a turtle? If so, why? Why
does the turtle need more protection than the snake or lizard?
7. Describe the color pattern of the turtle you are studying. Is this
arrangement of colors the same for others of the same species?
8. Describe the arrangement of the epidermal plates of the turtle's
shell. Are the arrangement, number, and form of plates the same for
all turtles of this species? Compare with the plates of other
species. What variations do you find?
Reptiles: A General Review and Library Exercise
1. Characteristics of reptiles.
2. Orders of reptiles. Characteristics and examples of each order.
3. Poisonous snakes found in the United States. The poison fangs of a
rattlesnake. Habits of the rattlesnake.
4. Cures for snake bites, fabled and real.
5. Snake charming.
6. Famous poisonous snakes and their habits.
7. The characteristics and habits of alligators.
8. The characteristics and habits of marine turtles. How they differ
from pond turtles.
9. For what is each of the following noted? Where does it live? The
terrapins? the horned toad? the Gila monster? the chameleon? the
glass snake?
10. Reptiles of former (geological) times compared with those of the
present.
11. Care of eggs and young. Swallowing of young by snakes.
12. Food of snakes. Defend the proposition that non-poisonous snakes
are beneficial and should not be killed wantonly.
13. Investigate and write an account of the economic value of
reptiles.
#D. STUDIES OF BIRDS#
#Vertebrates specialized for Flight#
The Living Pigeon
_Materials._
Living pigeons in cages, and, if practicable, other birds such as
chickens, canaries, and sparrows.
_The Body._
1. What divisions of the body are present? Compare the relative size
of these divisions with that of other vertebrates studied. Can you
account for the great increase in bulk of the trunk over the other
divisions? How do you account for the longer neck?
_Flight._
2. What is the shape of the body? How is the body made smooth? To
what is the shape and smoothness adapted? (Recall the appearance of a
plucked pigeon or chicken.)
3. Observe the size of the wings by measuring their width and spread
(measured from tip to tip when outspread). Where on the body are they
attached? How is this point of attachment advantageous? What is the
shape of the upper surface of a wing when spread? of the lower
surface? How is this shape advantageous in flight?
4. Where are the largest and strongest feathers? How are they
arranged with respect to each other: (a) to prevent air passing
through on the down stroke of the wing? (b) to permit folding?
5. What is the shape and width of the tail when outspread? when
folded? In what way does the tail assist in flight?
_Walking and Perching._
6. Identify the parts of the leg as in the frog. (See study of frog.)
With what exoskeletal structures is each part covered? How many toes
are there? Does the pigeon walk on its foot or on its toes? Where is
the ankle joint?
7. The bird's legs are arranged to support the body. How is this
brought about? Compare with the lizard and frog in this respect.
8. Explain how the legs are adapted (a) to preserve the balance of
the body, and (b) for perching. Are they well or poorly adapted for
locomotion? Explain. For what other purposes are the legs sometimes
used?
_Feeding and Drinking._
9. What is the form and character of the jaws of the pigeon (called
the beak)? Offer food, and watch the pigeons eat. How does a pigeon
seize and swallow food? Does it chew the food? Locate the crop. If
the pigeon chewed its food, would it have a crop? Why? How does a
pigeon drink? How does the chicken drink?
_Respiration._
10. What parts move in breathing?
11. Compare roughly the body temperature (by touch) of man, the
pigeon, and the frog. Which has the highest temperature? which the
lowest? How can you account for the higher temperature of the bird?
(Which of the three must be able to endure long-sustained effort?
What is the effect on your own body of long-continued effort?)
_Sense Organs._
12. Identify the eyes, ears, and nostrils, and describe their
location. What are the advantages in having the eardrum at the bottom
of a canal? Is there any disadvantage? What is the probable function
of the inner thin eyelid? How does it work?
13. Investigate the power of response of the special senses. Which
seems to be the most alert? State the experiments which you used and
your reasons for your answers to this question. Which senses are most
serviceable in finding food? in protecting against enemies?
_Protection._
14. In what different ways are feathers protective to the bird? Study
the arrangement of the feathers to find how protection is increased
in this way. How do the feathers and parts of feathers which lie next
the body differ from those which are on the outer surface? What parts
of the body are unprotected by feathers? How are these protected, if
at all?
15. Note the flexibility of the neck. Through what part of the arc of
a circle can the pigeon turn its head? How is this especially
important to birds?
16. What means of defense has the pigeon when attacked?
_Summary._
1. Make a list of the important adaptations of the pigeon, (a) to
flight, (b) to feeding, (c) to perching, and (d) to protection.
2. Which is the most highly specialized, the fish, frog, snake, or
bird? Give reasons for your answers.
3. In what various ways are feathers of use to the bird?
_Suggested drawings._
a. Side view of the head.
b. A foot.
c. A wing.
d. Side view of the pigeon.
Supplementary Studies of the Pigeon
These topics and questions should be answered from experience with
pigeons and observations of their habits and behavior, and from books
to be obtained from the school and public libraries.
1. The homing instinct of the common blue pigeon and of carrier
pigeons.
2. Nesting habits, number of broods and number of young in each
brood, feeding the young. Why is this method of feeding the young
necessary?
3. Varieties or breeds of pigeons. How the various varieties were
produced; how they are kept true; reversions of type.
4. Darwin's experiments with the pigeons; object of the experiment.
Whitman's experiments.
The Exoskeleton of the Bird: Plumage
_Materials._
Living birds, as perhaps pigeons, or mounted or stuffed skins,
separate feathers, portions of feathers, microscopes.
_Observations._
The pupils should study the arrangement of the feathers and their
variations in form and size, and should identify the following
principal kinds:--
_Contour feathers_, those feathers, generally broad, which cover the
body, giving to it its outline and color.
_Coverts_, those feathers which cover joints, such as the joints of
the wing and tail.
_Primaries_ or _pinions_, the long stiff feathers of the outside of
the wing, used in sustaining the bird in flight.
_Secondaries_, the shorter, more symmetrical feathers lying next and
over the primaries.
_Down_, soft feathers found on young birds and next to the skin on
some adults.
_Thread feathers_, best seen about the eyes, ears, and beak.
_Quill_, the bare stiff portion, one end of which is inserted in the
skin. Examine its internal structure.
_Vane_, the broad expanded portion, the part ordinarily seen on the
bird.
_Shaft_, the mid-rib of the vane.
_Barbs_, the delicate outgrowths of the shaft making up the vane.
_Barbules_, the subdivisions of the barbs, some of which are provided
with hooklets. These may well be studied microscopically.
_Questions._
1. How is the plumage arranged to offer least resistance to the air
in flight? How does a bird sit when exposed to the wind?
2. In a column write the names of the parts of a feather, and
opposite each part state its particular use.
3. Of what use are the hooklets on the barbules?
4. State and explain the peculiar position of the shaft of the
primary feather; of that of a contour feather.
The plumage of many birds contains all stages of feather
specialization, from down to pinion. Find as many of them as you
can on your specimen.
5. What reason can you assign for the fluffy base and the compact end
of the contour feather?
6. How much of the feather of a full-grown bird seems to be supplied
with blood vessels? How does this bloodless or full-blooded condition
affect the weight of the feather; of the plumage; of the bird?
7. How would the above condition affect the temperature of the blood
and of the body? Would it tend to cool the animal or to conserve its
heat?
8. Show how the air lying motionless amongst the plumage may serve
the same purpose as that in the packing of a fireless cooker or a
"thermos bottle."
9. How would the above condition affect the growth and repair of the
feather? What connection has it with moulting?
10. What kind of feathers forms most birds' "baby clothes"? What kind
forms the adults' "underclothes"?
_Suggested drawings._
a. A typical feather.
b. A feather of each kind.
c. A bird with wings outspread, showing positions of feathers.
d. The minute structure of a feather.
Birds and Migration
_To illustrate Distribution_
Work in the Laboratory
_Materials._
Bird skins or mounted birds, at least one representative of each
order and, better still, of each family of the birds which pass
through or remain in your neighborhood; specimens in a museum may
also be used. Some guide to the identification of birds, as Walter's
"Wild Birds in City Parks" or Reed's "Bird Guide." A good diagram of
a bird.
_Directions._
Your object here is to familiarize yourself with the appearance of
birds of different types, and with the terms used in describing them.
Study first a diagram of a bird and learn the terms and their
applications.
An important item in the description of a bird is its length. This is
obtained by measuring from the tip of the beak, over the curve of the
head, to the end of the tail. This measures a curved line and gives a
greater length for a bird than the straight line you would naturally
estimate. Train your eye by watching house sparrows (so-called
English sparrows) and fixing their length as a unit. They are called
six inches long, and in the field other birds may be measured by
them. The robin is ten inches long, and may be used to measure the
larger birds.
In describing the colors of birds, great discussions often arise
because pupils do not use terms correctly. Consult Chapman's "Birds
of Eastern North America" for a color key or chart, and train
yourself to observe colors carefully and name them correctly. You
will find more colors among birds than are given there, but the
chart will help you a great deal.
Study in the laboratory as many birds as you can. Try to get one of
each order at least and, among the perching birds, one of each
family. The answers to the following questions should be recorded
upon the blank outlines of birds, or else in the form of a table.
_Questions._
1. How long is the bird?
2. What is the general color of the upper surface; of the lower?
3. What are the markings or peculiarities of the head, if there are
any?
4. Note any peculiarities of the tail, as to shape, length, or color,
if there are any.
5. If the wings are not like the back, note their color, and, if
there are wing bars, note their number and color.
6. What are the markings on the breast, if there are any?
7. Note any other markings, as rump spot, etc.
8. What sort of beak has the bird?
9. What sort of feet has it?
10. Identify the bird, using any key or guide you have. Do not ask
any one to help you until you have exhausted your own resources.
Comparative Study of Birds
1. In what ways do the feet of birds vary? Give examples to
illustrate your answer. What are the principal results of these
variations?
2. In what ways do the beaks of birds vary? Give examples of the
variations and of the special uses of the beaks.
3. How do water birds differ from land birds; flesh-eating birds from
seed eaters; insect-eating birds from seed eaters; shore and swamp
birds from land birds?
Work in the Field
_Materials._
(1) Birds in the field, field or opera glasses, and bird guides. (2)
Some extra time, as field work is rather slow. (3) Considerable
energy, as birds rise early and may be up and away before the usual
hour for your appearance.
_Directions._
The object of this work is to become acquainted with the living bird,
to learn not only its name, but also some of its ways. You will need
to spend time to do this, and as a rule the more time you spend the
more you will see. Every time you go out after birds, _record at the
time_ every kind of bird you see, so that at the end of the season
you will know not only when each kind of bird came, but also how long
it staid. When you see a new bird, record immediately its colors,
markings, actions, notes, and anything else which may help you later
to identify it. Do not trust to memory nor to the inspiration of the
classroom. After weeks of observation, write the following summary.
Summary of the Results of Field Study of Birds
1. Over what length of time have your observations extended? Where
have you studied? What have you found to be the best conditions for
studying birds? How many birds have you identified?
2. When in the year do birds migrate; when in the twenty-four hours?
3. In spring migration which birds come first; which come last? What
reason is there for this order?
4. What may retard migration? What may hasten it?
5. What could prevent certain birds from ever coming here, or, if
they did come, from staying?
6. Name some birds which stay here permanently; some which come only
for the winter; some which come for the summers; some which merely
pass through, going and coming.
7. Can you see anything which may determine whether a bird will nest
here or farther north? If so, what is it?
8. Why is the house sparrow so successful?
9. Why are blue jays so nomadic in winter?
10. What months do the herring gulls stay here? When do they leave?
Where do they go when they leave? What do they do while they are
gone? When do they return? What is their economic value?
11. How many birds' nests have you seen this spring? To what kinds of
birds did they belong? If you have been able to study one in
particular, give its history as far as you know it.
12. Tell what you have learned by your own observation this spring
concerning the kinds of food birds eat, and their methods of
obtaining food.
13. What bird songs have you learned to know? When do these birds
sing most? Does a bird have more than one song?
14. What birds have you seen near your home? What attached them to
the vicinity? How might you attract more birds?
Birds; Review and Library Exercise
1. What are the distinguishing characteristics of birds?
2. Give the orders of birds, with the characteristics of each order
and an example of each.
3. Define and give illustrations of the meaning of the expressions:
"land birds;" "water birds;" "shore birds;" "swamp birds;"
"scavengers;" "policemen of the air."
4. Discuss the temperature of birds, the amount of energy they show,
and the oxygen they use.
5. Beaks of birds.
6. Feet of birds.
7. The crop and gizzard. Why absent in many birds?
8. What is there in a bird's construction which enables it to twist
its head so far around? What are the advantages in being able to do
so?
9. Account for the oiliness of plumage of water birds; for the
complete feathering of legs and feet in some forms.
10. Define moulting and discuss its advantages and disadvantages.
11. Give reasons why you would not expect a bird to hibernate.
12. Name two or more kinds of birds which show "recognition marks."
What sort of birds would you expect to find with such marks? Why?
13. Is a bird's egg alive when it is laid? Why does it have so much
food stored in it? What direct interest have we in this fact?
14. How are the eggs of various birds protected while they are
developing?
_Note._--Do not be satisfied with only one way. A bird seldom is.
15. Compare præcocial and altricial birds as to their stage of
development when hatched; the location and character of the nest; the
care given by the parents; the singing habit of the parents; the
success of the type.
16. Name at least three insect-eating birds and tell how many insects
it is estimated each will destroy in a day. Effect in a garden?
17. If you had an orchard to protect from insects would you spray it
with poison, or would you police it with birds?
_Note._--Consider both sides. There is much to be said on each.
If you decided that you needed more birds, how would you get them?
18. Suppose you had a city lot in the suburbs, 50 feet wide by 200
feet deep, with a house covering the first 50 feet. Make a plan of
the back yard to show what you could do to attract the birds to it in
the summer; in the winter. Remember that birds must have protection
against enemies as well as against changes in weather, etc.
19. For what purposes are birds killed by man? Which of these do you
consider legitimate? Which birds may not legally be killed at any
time of the year in this state? Which may at certain seasons? Which
may at any time? When should an "open season" be permitted? How long
should it last?
20. Give a short biography of Audubon. Describe the purpose of the
Audubon Society and some of the work accomplished by it.
21. When were the house sparrows, or, as we call them, the English
sparrows, introduced into this country? Where? Why? Have they proved
a success from our standpoint? From their own? Why have they
increased so enormously? What part of the country is still free from
them? Why? Give the reasons for and the methods of fighting English
sparrows.
22. The history of the passenger pigeon.
23. What has the quail or bobwhite to do with our food supply?
24. Poultry keeping.
25. Name three bird magazines and give a characteristic of each one.
26. Fossil birds and the light they shed on the probable ancestry of
birds.
Study of the Migration of Animals in General
The migration of birds is only one case of a phenomenon which is
comparatively common. From your text and reference books find other
examples of migration. What are the causes which make animals
migrate? What methods do various animals use? What are some results
of these migrations? Summarize your study in the following thesis:--
_The distribution of animals._
1. The necessity for this distribution.
2. Methods of distribution--voluntary--involuntary.
_Note._--See in review the methods used to spread corals,
hydroids, and other sedentary forms, starfish, clams, etc., as
well as those used by the various vertebrates.
3. Time when migration occurs. Consider here the young of most
animals, and the movements of many birds, as well as movements caused
by some accidental occurrence.
4. Distance that animals move from the place of their birth.
5. Factors which determine the routes of distribution.
6. Factors which limit distribution.
_Migration maps._
1. A map to show the migration route of the birds of your region.
2. A map to show the migration of the potato beetle (or English
sparrow or any other animal the extension of whose range has been
studied).
3. A map of the world, showing the zonal areas.
4. A map of North America, showing the distribution of the ungulates,
with the boundaries and barriers marked.
5. A map of North America, showing the distribution of the
fur-bearing animals.
6. A map of the world, showing the distribution of the human races.
#E. STUDIES OF MAMMALS#
#To illustrate Man's Relation to Other Animals; the Connection
between Mode of Life and Structure#
The Rabbit
_The effects of domestication upon an animal. A burrowing type of
rodent._
_Materials._
Living rabbits--young rabbits are more desirable for laboratory
study.
_Observations._
_The Body._
1. What divisions of the body are there? Compare the length and use
of the neck with that of the pigeon. Describe the character and
length of the tail. What use has it, if any?
_Locomotion._
2. What methods of locomotion has the rabbit? Which is most commonly
used?
3. Study the limbs, and find the ankle and wrist. Does the rabbit
walk on its foot or its toes? Note the number and character of the
toes and fingers and their claws. What is the effect of the
nonretractile power of the claws upon the uses to which claws can be
put?
4. What uses have the fore or the hind limbs other than locomotion?
Explain how the usual sitting or resting posture is advantageous for
quick locomotion.
5. By means of printer's or writing ink smeared over the soles of the
feet, and a long piece of clean white paper get prints of a rabbit's
tracks as it hops over the paper. Explain how the peculiar formation
of the tracks occurs.
_Feeding._
6. Offer a rabbit various kinds of food. How does it test the food
before eating? Does the rabbit ever use its forelimbs to assist in
feeding? If so, when and how? How is the food eaten? How are the
teeth fitted for the rabbit's method of feeding? Does your rabbit
drink? If so, how?
_Respiration._
7. What movements of the body are concerned in breathing?
8. Compare the frequency of the breathing movements with your own.
Can you distinguish the heart beats? If so, how and where? Count
them.
_Sense Organs._
9. Note the position of the eyes, shape of their surface, shape and
size of the pupil. What external protecting structures are
present,--such as eyelids, eyelashes, eyebrows? Study the movements
of the eyelids. Is there a third eyelid as in the bird? Compare the
use of the neck in enlarging the range of vision with that of the
bird. Is the rabbit's range of vision greater or less than your own?
10. What is the location of the nostrils? What advantages are gained
by the prolongation of the face forward? Note any peculiarity in the
form or movement of the nostrils. How do you explain these movements?
Are the nostrils more or less useful than those of other vertebrates
you have studied? How?
11. Note the shape, size, and position of the external ears and
explain what relation, if any, these characters of the ears have to
hearing. Note the various movements of the ears and the reasons for
these movements.
12. What special organs for touch has the rabbit? Under what
circumstances are these of use? What parts of the body are most
sensitive to touch?
_Protection._
13. What home-making habits do you observe in the rabbit? What habits
relating to secrecy, comfort, and safety, do you observe?
14. Study the fur and hair of the rabbit. How do you distinguish
between fur and hair? What variations do you find in the fur and
hair? What parts of the body are uncovered? Why? What are the various
functions of the fur and hair covering of rabbit?
15. Have rabbits any means of defense or offense? Explain.
_Social Habits._
16. Notice and describe anything in the behavior of the rabbits which
may be classed as social,--such as play, fondness for company,
display of affection, homing instincts, care of young, etc.
Supplementary Study of Wild Rabbits
If you cannot answer these questions from observations of wild
rabbits, the answers may be obtained by reading some good natural
history. Ernest Thompson Seton's story of a rabbit's life is good for
the purpose.
1. What method of locomotion is more highly developed in wild rabbits
than in domestic rabbits? Why?
2. When do wild rabbits do their feeding? Why? In what ways do they
sometimes do damage in feeding?
3. What senses will probably be more alert than those of the domestic
rabbit? Why?
4. Where do wild rabbits usually make their homes? Why? How do they
guard against being cornered in their homes?
5. In what ways do they guard against surprise when feeding? What are
the principal enemies of rabbits? What devices do they employ to
escape enemies when pursued by them? What is thumping? When used?
6. How many young rabbits are usually produced at one time? How many
litters in a season? How long does it take a young rabbit to mature?
7. How are the young of rabbits guarded against danger from enemies
and weather? What are the various causes that tend to keep down the
numbers of rabbits?
8. Give an account of the plagues of rabbits in Colorado and
Australia, including the reasons for the great increase in numbers
and the methods used to destroy the rabbits.
Summary of the Study of Rabbits
1. What has been the general effect of domestication upon rabbits?
2. What are the most important characters and habits that fit the
wild rabbit for its life?
The Guinea Pig or White Rat
_Materials._
Living animals.
_Observations._
1. What regions of the body can you identify? What is the relative
length of the neck, ears, legs? What about the tail?
2. Describe the color scheme of the animal. Is it protective or the
result of breeding? What is the character of the covering?
3. Describe the method and rate of locomotion. Would this method of
locomotion enable the animal to escape from enemies (_e.g._ dogs)?
4. What is the shape of the foot? What is the shape and length of the
claws? For what are they adapted?
5. What sounds do the animals make?
6. What is the appearance and shape of the eye? What is the color of
the eye?
7. State the size and shape of the external ear. What movements are
characteristic?
8. What motions of the nostrils do you see?
9. Feed the animal various kinds of food. How does it eat? State any
facts you observed, to show that it has or has not a choice as to
food.
10. Watch the animal for some time to determine its mental
characteristics. Is it alert? curious? timid? Does it show much
intelligence? affection?
What is the relation between mental development and success in
the struggle for existence?
_Summary._
1. What are the general characteristics of the animal?
2. To what kind of life is it adapted?
3. What are some of the characteristics that make the animal a good
pet?
The Squirrel
_Materials._
Living specimens in cages, mounted specimens, pictures, charts,
lantern slides, etc.
_Directions._
Before taking up the study of the squirrel in the laboratory a trip
should be made to some park or wooded region and the habits of
squirrels noted. Take your camera and try to take some snapshots.
After the laboratory exercise visit some museum or zoölogical garden
and study the relatives of the squirrel.
_Observations based upon field work._
1. What different postures does the squirrel assume?
2. What does it do when frightened?
3. What use have the forelegs other than locomotion?
4. How does a squirrel go up a tree? down? from branch to branch?
State all the forms of locomotion you have noticed.
5. What is the appearance of the tail? What is the position of the
tail when the squirrel is sitting? running? on a branch? Describe any
motions of the tail you noticed. Is there anything expressed by these
motions or are they without meaning?
6. Tempt the squirrel with some nuts. State the evidence that leads
you to think that the squirrel is alert, timid, curious. Do you
think the squirrel acts most from instinct or as the result of
intelligence?
7. In what various ways does a squirrel attempt to escape notice?
What does it do when you chase it?
_Observations in the laboratory._
1. What divisions are there to the body? What is the length of the
neck? the length and appearance of the tail?
2. What is the relative length of the legs as compared with the body?
How does the length of the front and hind legs compare?
3. Does the animal walk on its toes or on the sole of its foot? How
many toes on each foot? What is the length of the claws? For what
could they be used?
4. Offer the squirrel various kinds of food and see if it has a
choice. Describe its methods of eating.
5. Note the position of the eyes, the shape of their surface, and the
shape and size of the pupil. How many eyelids do you notice? Why do
the squirrel's eyes appear so "bright"? Are eyebrows, eyelashes, or
tear glands present?
6. Note the size, shape, and appearance of the squirrel's external
ears.
7. What movements of the nostrils do you notice? For what does a
squirrel chiefly use his nostrils? What explanation can you suggest
for the nostrils, eyes, and ears having the same relative position in
all vertebrates?
8. How does a squirrel protect itself?
9. Smear the feet of a squirrel with ink and allow it to run over
a roll of clean paper as in the case of the rabbit. How do its
tracks differ from those of the rabbit?
_Summary._
1. What are the general characteristics of the squirrel?
2. To what kind of life is it adapted?
3. What adaptations has the squirrel to protect it from its enemies?
4. What characteristics make the squirrel a good pet? What objections
to it?
Library Exercise on Rodents
1. General characteristics and examples of rodents. The teeth of
rodents.
2. Show how variation in habitat depends upon structure among rodents
by comparing, for example, squirrels, beavers, and woodchucks.
3. Variations in the tails of rodents. What are the causes of this
variation?
4. Pocket gophers and their economic relations.
5. Species of mice. Their habits.
6. The dancing mouse.
7. Damage by mice. Plagues of field mice in Nevada. Method of
extermination.
8. Habits and kinds of rats.
9. Economic importance of rats. Methods of extermination.
10. Rats and the bubonic plague.
11. Squirrels, kinds and habits.
12. The economic value of rabbits.
13. The groundhog myth. Habits of woodchucks.
14. The beaver--their habits and sagacity. Methods of trapping them.
15. Prairie dogs--their habits and economic importance. How
exterminated?
16. What are porcupines?
17. Variation in the homes among rodents. Usual means of defense.
18. Make a list of rodents in a column, and in another column
opposite each name write the various ways the animal is of economic
importance. Sum up with a statement showing the most important ways
rodents are of value to man and harmful to man.
19. Defend the proposition that rodents are on the whole harmful
animals and should be exterminated.
20. How some rodents contribute to the science of medicine, more
especially to bacteriology.
The Cat or Dog--Carnivora
_Materials._
Living specimens of cats or dogs. Pictures, books, lantern slides,
etc. Supplement the laboratory study with trips to museums and
zoölogical gardens to observe the relatives of the cat.
_Definitions._
_Carnivora._ An order of mammals, chiefly flesh-eating, with claws
and well-developed canine teeth.
_Carnivorous_, flesh-eating.
_Herbivorous_, plant-eating.
_Omnivorous_, eating both plants and animal food.
_Digitigrade_, walking on the toes.
_Plantigrade_, walking on the soles of the feet.
_Vibrissæ_, long hairs on the face--"whiskers."
_Observations._
1. Into what regions is the body divided?
2. What is the shape of the head and the length of the neck?
3. Are the legs relatively long or short? How do the front and hind
legs compare in length? How many toes on each foot? Is the cat
digitigrade or plantigrade?
4. How many pads on the sole of the foot? What use can you suggest
for these structures? What is the size and shape of the claws? Are
they retractile or nonretractile? For what purposes may the claws be
used?
5. Describe the tail as to length and appearance. Movements.
6. What is the size and appearance of the external ears? What
movement do you notice?
7. Are the eyes large or small? What eyelids can you find? What other
accessory structures? What is the shape and direction of the pupil?
8. What other sensory structures do you find? What is their function?
9. Watch the animal eat. Does it chew or "fletcherize" its food?
What teeth seem well developed? Is the movement of the jaws simply up
and down, or is there a lateral movement as well?
10. Try to find out some of the mental characteristics of the animal,
_i.e._ is it sluggish or active? Is it alert? Does it show curiosity?
fear? What evidence of intelligence?
_Supplementary studies._
a. Smear the feet of a cat with ink and allow it to run on a sheet of
clean paper. Make a diagram to show tracks. Do the same in case of a
dog. How do these tracks differ? Why?
b. What is the difference between a cat and a dog as to the manner of
eating a bone?
c. As you see dogs and cats outside do you see any evidence in either
case of a tendency to gather in packs (gregariousness)?
d. What different emotions are expressed by a dog's tail? a cat's
tail?
e. What sounds do cats and dogs make? Significance?
f. Contrast the sleeping habits of cats and dogs.
g. How large is the litter in case of dogs and cats? Condition of
young at birth? How long before the eyes of the young are open? Care
of young.
_Summary._
To what kind of life does a cat or dog seem best adapted: (a) as to
food? (b) protection from enemies?
Carnivora; Review and Library Exercise
_Characteristics._
1. The general characters of carnivora.
2. Five important families. The characteristics and examples of each
family.
_Morphology and physiology._
3. The dentition of the cat, the dog, and the bear. Variation in the
"chewing teeth."
4. Three types of paired appendages among carnivora. Relation to
habitat.
5. The difference in structure and use of the posterior legs of the
seal and walrus.
6. The alimentary canal of a cat and rabbit compared.
7. The tongue of cats and dogs contrasted as to structure and use.
_Economics._
8. The difference between hair and fur.
9. The fur-bearing carnivora. Families, and habitat.
10. Trapping.
11. Game laws and game wardens. Hunters' licenses.
12. Hunting big game.
13. Carnivora harmful to man.
14. Carnivora useful to man.
15. Carnivora as pets.
16. Chief types or breeds of domesticated dogs. Characteristics.
Special value of each.
17. Chief types or breeds of domesticated cats.
18. Dogs as burden bearers.
_Natural History._
19. Distribution and range of carnivora. Carnivora of the United
States.
20. Winter habits among carnivora.
21. Food of carnivora. Various methods of obtaining it.
22. The hunting habits of the dog and cat family.
23. The habits and distribution of the raccoons.
24. The color schemes of the more important families of the
carnivora.
25. Seasonal variation in color.
26. Distribution and habits of the ferrets and weasels.
27. How carnivora protect themselves from enemies. Which carnivora
have been most successful in resisting man's advance?
28. Peculiar and interesting carnivora to be seen in museums and
zoölogical gardens.
29. Origin of the domestic dog.
30. Intelligence of dogs.
31. Fox-hunting.
32. Coyotes and their relation to stock raising, etc.
The Ungulates
_Materials._
Pictures, charts, lantern slides, and books showing cow, sheep, hog,
goat, horse, etc. Diagram of skeleton.
_Directions._
Since it is impossible to have living ungulates in the laboratory,
this study should be supplemented by trips to a museum and to a
zoölogical garden. Observe also such hoofed animals as may be common
in your neighborhood. Use your camera and make "snapshots," showing
characteristic attitudes of these animals.
_Definitions._
_Ungulates_, an order of mammals characterized by the possession of
hoofs.
_Ruminant_, a division of ungulates, which "chew the cud."
_Perissodactyl_, a division of ungulates with an odd number of toes.
_Artiodactyl_, a division of ungulates with an even number of toes.
_Carnivorous_, flesh-eating.
_Herbivorous_, plant-eating.
_Omnivorous_, eating both plant and animal food.
_Observations in the laboratory._
_Note._--Answer the following questions for one or more of the
following: The cow, sheep, goat, hog, and horse. If desired, the
questions may be answered in the form of a table.
1. What is the relative length of the neck? What is its direction
with reference to the body? Of what importance is this length and
direction?
2. What is the length and appearance of the tail? What is its use?
3. What is the relative length of the legs? Locate the heel, knee,
and elbow. (Reference should be made to a diagram of a skeleton.)
When the leg is long, in which bone is this lengthening accomplished
(compared with human skeleton)?
4. How many toes on each foot? Is the animal an artiodactyl or a
perissodactyl? Is it plantigrade or digitigrade?
5. What is the relative size and position of the ears (external ear)?
6. What is the relative size and position of the eyes? nostrils?
7. Are horns of any kind present? If so, note the size, shape, and
direction. Are they present in both sexes? If not, in which one? If
in both, note any differences distinguishing the sexes.
_Suggested drawings._
a. Head, side view.
b. Entire animal, side view.
_Observations in the field or at home._
1. Note how the animal uses its lips, tongue, and teeth in feeding.
Is it a ruminant?
2. In what order does the animal use its feet? Look up the definition
of _walk_, _run_, _gallop_, _canter_, _trot_, _lope_, _single foot_,
_pace_. Which of these forms of locomotion are optional with the
animal?
3. Describe the process when the animal lies down and gets up.
4. Describe the covering of the animal, noting its length, fineness,
etc. What variations in different regions of the body?
5. Is the animal alert or sluggish? Upon what senses does it most
depend? What mental characteristics are most marked, _e.g._
curiosity, fear, suspicion.
6. Note any movements of the ear. What is gained by these movements?
7. What is the position of the eye? What is the shape and direction
of the pupil? Reason?
8. What means has the animal for getting away from its enemies.
_Observations based upon museum trip or natural history._
1. Identify as many ungulates as you can; for example, buffalo, musk
ox, big-horn sheep, Rocky Mountain goat, chamois, antelope, giraffe,
red deer, elk, moose, reindeer, wild boar, peccary, rhinoceros,
zebra, hippopotamus.
2. Answer the following questions about each:--
a. What is the family, scientific name?
b. What is the size of the animal? the relative length of the hind
and fore legs? the relative length of the neck?
c. What is the nature of the covering of the animal?
d. Are any horns developed? If present, what is their size, shape,
direction, and appearance?
e. What is the habitat of the animal? its distribution and social
life?
_Summary._
In a short thesis summarize the facts you have found out about
ungulates, using the following outline:--
1. Why called ungulates? Variation in number of toes.
2. General fact about the food of ungulates. The two divisions.
3. The general adaptations for protection.
4. The social life of the ungulates.
5. The native ungulates of the United States.
6. Commercial uses and value.
Ungulates: Review and Library Exercise
_Characteristics._
1. Classification of ungulates based upon number of toes, kind of
horns, "chewing the cud," etc. Some of the more important families
with examples.
_Morphology and physiology._
2. The variation in the number and kinds of teeth. The dentition (or
dental formula) of horse and cow.
3. The various types of horns. Shedding of horns and sexual
variation.
4. The structure and function of the stomach of a ruminant. Meaning
of the cud-chewing habit.
5. The structure of the stomach of a camel.
_Economics._
6. Ungulates which have been domesticated.
7. Breeds of cattle--their distinguishing marks and valuable points.
8. Breeds of horses--their distinguishing marks and valuable points.
9. Breeds of sheep--their distinguishing marks and valuable points.
10. Breeds of hogs--their distinguishing marks and valuable points.
11. Angora goats.
12. The making of butter and cheese. Kinds of cheese. Substitutes for
butter.
13. The packing industry. Ungulates useful as food.
14. The various methods of preserving meat.
15. Cattle ranches and "round-ups." Free cattle in winter.
16. Cattle raising in your state; in other countries.
17. Transportation of cattle. Stock cars, care and feeding.
18. Useful products derived from ungulates.
19. Tanning. Varieties and use of leather.
20. Diagrams showing chief cuts of meats.
21. Sheep husbandry. Shearing.
22. Ungulates as beasts of burden. Advantages and disadvantages.
23. Government inspection--quarantine.
_Natural History._
24. Geographical distribution of ungulates. Habitat and range.
25. Native ungulates of North America.
26. How, when, and by whom cattle and horses were introduced into
America.
27. The geological history of the horse.
28. The story of the buffalo.
29. Deer hunting.
30. Methods of protection from enemies among ungulates.
31. Breeding habits and care of young in case of ungulates.
32. Intelligence in the case of horses.
33. Strange and peculiar ungulates to be seen in museums and
zoölogical gardens.
The Horse
The pupil is expected to study carefully the account of Eohippus or
Hyracotherium in his text or any other available reference book, and
to supplement that work and this brief sketch with original
observations upon horses on the street, at a local store, or wherever
possible or convenient.
From the early horses which migrated from North America there arose
in Asia and Africa the ass, famous in the history of early
civilization and still used in some localities as beasts of burden or
for the breeding of mules, which are the crosses between ass and
horse. There also arose the zebra and the most primitive of modern
horses, Przewalskii's horse, a wild pony of western China, about
forty inches high and almost identical with the drawings of the horse
made by early man, 30,000 years ago. Doubtless the modern ponies of
Ireland, Iceland, and Shetland are descendants of the original
Przewalskii type and not, as is often claimed, true horses stunted by
rigors of climate and scant fare.
The horse is characterized largely by the presence of a lock of hair
between the ears, a full mane and tail, small ears, large hoofs, and
peculiar neigh. The ass has no forelock, a scanty mane and tail, long
ears, small hoofs, and a distinct bray.
By means of various crusades and raids, the modern horse was
introduced into Europe from Asia, where it is clearly traced in
history to the reign of King Solomon. Here, in Europe, because of
local conditions and demands, it assumed differing type forms. The
roadster type is closest to the Arabian in character. The draft or
heavy type was bred in western Europe when heavy armor came into use
for rider and horse, and the coach or carriage type was developed
when armor was abandoned for gunpowder. Finally explorers and
colonists brought the horse back to America, its original home.
The various types and varieties may be briefly described.
_A._ The draft type has short legs, short neck, large round body, and
ranges in weight from 1400 pounds to 2000 pounds.
_Varieties:--_
1. _Percheron_: generally about 1700 pounds in weight, 16 hands (64
inches) high, gray or black, blocky body, steep rump, clean legs, and
quick action.
2. _Shire_: generally about 1800 pounds in weight, 17 hands high, bay
or brown, white marked feet and face, hairy legs and feet, and slow
action.
3. _Belgian_: generally about 1800 pounds in weight, 16 hands high,
chestnut or roan in color, compact body, short, steep rump, and small
feet.
_B._ The coach or carriage type has legs and neck of medium length, a
body full-chested but not blocky, and a weight varying from 1150
pounds to 1400 pounds.
_Varieties:--_
1. _Hackney_: generally of full, broad, powerful body, short legs and
back, high action and high carriage of neck and head, bay or chestnut
in color, 15 hands high, and 1400 pounds in weight.
2. _Coach_: generally lighter than the Hackney, with longer legs and
long stride; height, 16 hands; weight, 1300 pounds.
3. _Cleveland bay_: averaging 16-1/2 hands in height, 1350 pounds in
weight, high, broad hips, strong action, and bay color.
_C._ The roadster type is long and lean of limb and body, and
averages about 1100 pounds in weight.
_Varieties:--_
1. _Thoroughbred_: of small head, long neck, level back, of variable
color, 14-1/2--16-1/2 hands high, about 1000 pounds in weight.
2. _American saddle_: an American production; not a distinct breed,
but a roadster of high quality.
3. _American trotter_: a superior type of good speed. The off
forefoot and the nigh hind foot act together, the nigh fore and the
off hind feet together, giving a two-beat gait.
4. _Pacer_: similar to the trotter, but using both off feet and both
nigh feet together, giving a swinging gait.
The horse is very similar to man in its physical and mental
character, being subject to the same ailments and treatment and
having the same impulses of affection, hatred, fear, jealousy,
obedience, willfulness, memory, and perhaps reason. It is of all
animals most careful in its eating and drinking; because its stomach
is small, the food should not be bulky but concentrated, grain
forming a goodly portion of the ration.
Perhaps the most important point in the structure of the horse is the
form of the leg and foot. The shoulder should slope slightly backward
and the pastern joint, immediately above the hoof, slightly backward.
The hips, or "quarters," should slope downward somewhat, and the
hock should be comparatively wide to afford ample leverage for the
pulling muscles. The legs should be straight as pillars when seen
from front or rear. The outer walls of the hoof support most of the
weight though the frog should normally touch the ground. In nature
the hoof wears away properly of itself, but the shod hoof needs
regular trimming attention, while the frog must not be trimmed, for
it is the soft growing part that nourishes the hoof. In this
treatment the foot is comparable with the human finger and finger
nail.
_Observations._
If access to a living animal is impossible or inconvenient, the pupil
may use reference book or pictures for most of these points. A
measuring tape or ruler should be at hand, and the assistance of an
experienced person is a valuable aid. If several horses are studied,
they should be distinguished by name or number.
Record the color, condition, weight, and height of the horse at the
shoulder. (Height is given in "hands," a hand being the breadth of
the palm, or 4 inches.) Note the slope of the shoulder, of the back
and the hips, the general form of the head and neck, and the facial
expression. Find the chestnuts, warty growths on the inside of each
leg. Examine the foot, finding the V-shaped frog in the center,
surrounded by the horny hoof.
Find the pulse by passing the fingers downward from the upper curve
of the neck, along the inside of the jaw; count the pulse. Notice the
position and motion of the ears with their lining of hair, and the
position of the eyes, the form of the pupil, and the probable range
of vision. Watch the horse use its lips, and examine the mouth and
teeth, finding the grinding teeth far back in the mouth, the incisors
in front, and the space where the canines are missing.
The male may have canines in the upper jaw.
On the surfaces of the incisors are the depressions, or "cups," by
means of which age is determined.
At six years the cups leave the lower center teeth; at seven the
adjoining teeth; and at eight, the outer lower teeth. At nine
years they leave the upper center incisors; at ten, the adjoining
teeth; and at eleven, the outer teeth above. At the age of ten
years a spot appears in the outer upper incisors, at fifteen
years the groove has worn to the center of the tooth, and at
twenty-one years the groove is worn to the bottom of the tooth.
_Questions._
1. Describe the horse you studied as to its name or number, its
color, markings, weight, and size. Of what type and breed is it a
specimen?
2. Upon how much of the foot does the horse walk? How does this
affect ease or speed of action? How does an athlete imitate this in
sprinting?
3. How many toes has each foot? What advantage or disadvantage can
you see in this unusual structure?
4. How is the hoof constructed to distribute the weight over a
surface broader than the leg? How general is this among terrestrial
animals?
5. What is the difference in the position of the chestnuts of the
fore and hind legs?
6. Where in the foreleg is a springiness permitted by curvature?
Where does the back leg accomplish the same thing?
7. How do you account for the elongating of the face?
8. Explain the uses of the lips, telling how they are fitted for
their work.
9. Tell where the bit lies in the horse's mouth, and how the
structure permits this.
10. Where are the ears situated? How does this peculiar position
affect the range of hearing and general alertness? Of how much
movement are they capable? Describe the lining of the ear, and state
its use.
11. What is the rate of the pulse?
12. Measure the height at shoulder and at croup, length of body from
withers to rump, of head, of neck; thickness of body from the
shoulder to the chest and of distance of chest from ground. Point out
any equalities or ratios you find.
_Topics for investigation._
1. The meaning of the terms _gee_, _haw_, _nigh_, _off_, _run_,
_gallop_, _trot_, _pace_, _single foot_, _rack_.
2. The location, cause, and effect of these troubles: heaves, blind
staggers, knee sprung, shoe boil, quitter, ring bone, spavin, capped
hock, flat foot, hoof bound, glanders, mange, sweeny, hide bound, and
thrush.
3. The record time for a trotted and a paced mile.
4. The meaning of "one horse power." How much a horse can pull on
good roads.
5. Record prices for valuable horses.
6. Current prices for horses; for ponies; for mules.
7. The origin and the use of the mule.
8. Balanced rations.
9. The number and care of the young, and their relative development
at birth.
10. Other animals used as beasts of burden in peculiar conditions or
localities.
Homology of the Vertebrate Skeleton
_Materials._
Prepared skeletons of an amphibian, a reptile, a bird, another
mammal, and man. If any of these be lacking, lantern-slide
illustrations may be used in a partially darkened room.
_Observations._
Having studied the frog's skeleton in detail, the student can readily
compare each of these types with it. Compare in a very general way
the skulls, the girdles, and the limbs; their form and use. Note
variations in the form and number of the vertebræ and the number of
the ribs.
_Questions._
1. In which types of vertebrates are the joints between the skull
bones bound with cartilage? How does the joining change in later
types?
2. What dissimilarities occur in the series as regards closure or
boxing in of the eye orbits, nostrils, and skull bones? How would
these changes in joining and closure affect strength, rigidity, and
protection?
3. What evidence is there that such improvement has affected brain
capacity and intelligence?
4. State how the attachment of the skull to the vertebral column
changes as the animal man assumes an erect position.
5. Are the vertebræ of these types alike in structure? What is the
general form of an horizontally placed vertebra, as in the horse or a
reptile, and of a vertically placed one, as in man? If you see any
differences, account for them.
6. Wherever possible, find the vertebræ of the neck (cervical), and
note the number of them in each case.
7. How is flexibility of the column accomplished in certain types or
in certain places of one type? How is rigidity gained? State
instances in each answer.
8. Examining the interior of the turtle's "shell," find out and
explain how the vertebræ have been modified to form the upper
"shell." How has the under portion (_plastron_) been formed?
9. In round numbers, which skeleton has the greatest number of
vertebræ and which the least?
10. Which skeleton has the greatest number of ribs, and which has the
least?
11. In a summarizing statement explain any variations you find in the
pectoral and pelvic girdle for strength (rigidity); flexibility. This
answer may be written as a table, naming the bones, opposite each
stating its condition, and then what it affords or is adapted to.
12. What is accomplished by having two bones in the shank of the leg?
In what types or forms is there but one, and which one is it?
13. Can you assign any advantages in power, agility, length of leg,
or position of leg and foot accruing from a long ankle? (See horse,
frog, _et al._)
14. Enumerate the types or forms, and opposite each state the number
of fingers and toes.
15. Make a table, heading one column "Form or type"; another,
"Habitat"; and a third, "Habit." Judging from the structure which you
see or from your previous knowledge or experience, fill in the table,
stating whether the type is aquatic, terrestrial, or aërial; whether
it burrows, walks, runs, or climbs, etc.
16. From your statements in 15, explain how the peculiar mode of life
affects the structure of these types.