Harriet Randolph.

Laboratory directions in general biology online

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with the second maxilliped, and by refer-
ence to the chart * determine the homolo-
gous parts in the series.

Find the scaphognathite. Of what parts is it
made up ? In what way can it move ?

Of what parts is the telson composed ?

Diagrams of :

The third abdominal appendage.

* Enlarged from Plate VIII, The Appendages of the Crayfish,
in "The Atlas of Practical and Experimental Biology," G. B.


The posterior thoracic appendage.

The fifth thoracic appendage.

The fourth thoracic appendage.

The second maxilliped.

The first maxilliped.

The second maxilla.

The first maxilla.

The mandible.

The antenna.

The antennule.



Keeping the specimen moist, observe :

I. General Characters.

1. Stem : erect and unbranched (or branching

only from the base).

2. Leaves : pointed at one end. Attached to the

stem without a stalk (i.e., sessile),

3. Rhizoids : at the base of the stem (often

hidden by the sand, etc., clinging to them j
to see them distinctly, rinse in water).

4. Flowering heads.

(a) In male flowers a terminal rosette of stiff

green leaves (perichsetium) surrounding
the antheridia.

(b) In female flowers a terminal bud formed

by the folding together of terminal
leaves that enclose the archegonia.

II. Histology.
1. Stem.

Remove the leaves near the base of the stem ; until
a razor make a thin transverse section, mount in
water, and observe :

(a) The thin epidermis (best seen in young



specimens), and the subepidermis : a
conspicuous brown layer.

(b) Next to this a region of nearly colorless

cells. Compare these with (a) in regard
to cell-contents and thickness of cell-

(c) In the centre a central or axial strand.
Make a diagram showing the outlines of the different

regions. Sketch a few cells of each kind to show
tlieir characteristics.

Make a longitudinal section, mount in ivater and
find the same regions. Sketch carefully to the
same scale a few cells of each kind.

2. Leaf.

Mount in water a young leaf of a more delicate
species of moss as Mnium and study with D 2
to see :

(a) The structure, a thin lamina with a thicker

median region, the midrib.

(b) The margin of the lamina.

Sketch two or three cells at the edge of the leaf to
show the character of the margin.

3. Ehizoids.

Mount in water. With D 2 note :

(a) Cell-contents.

(b) Any difference that is observable between

the younger and the older rhizoids.

4. Reproduction.

MOSS. 77

A. Male Plant. Sketch.

With a razor make longitudinal sections of the
flowering head. Mount in ivater and observe at
the apex of the axis within the perichcetial leaves :

(a) Antheridia : oblong sacs with a wall of a

single layer of cells. Within the sacs
are mother-cells of antherozoids.

(b) Filaments (paraphyses).

(aa) Hairlike.
(bb) Spatula-shaped.

Sketch an antheridium from the surface and in op-
tical section.
Sketch each kind of paraphysis.

B. Female Plant. Sketch.

With needles separate the leaves from the, top of the
axis of the female flowering head and search for:

(c) Archegonia : flask - shaped bodies with

elongated neck and enlarged ventral
part containing the oosphere.

(d) Paraphyses.


Observe :
I. General Characters.

1. The slender stalk, seta, which supports :

2. The capsule, which contains the spores.

The parts of the capsule :

(a) The thick hairy cap, calyptra.


Take off the calyptra and by reflected light note
beneath it :

(b) The operculmn.

Sketch the capsule with the calyptra removed. Take
off the operculum and observe :

(c) Around the rim on which it rested, the

teeth of the peristome.

(d) Stretched across between the tips of the

teeth, the epiphragma partially closing
the spore-case.
Divide the capsule transversely and make a diagram

of the cut surface.
Examine and sketch a spore.

Examine with the naked eye some living moss-


Mount some of the protonema in water; with needles
gently separate the green .filaments; cover and
examine with D 2. Observe :

1. The green branching filaments made up of


2. Growing out in places from the protonema

buds developing into moss-plants.
If observed, sketch.

* Found growing as a green encrustation on banks of earth
without much other vegetation, by roadsides, etc., in partly
shaded places, especially those exposed to the north.



I. Gymnosperm,

Make with a razor thin sections transverse, radial,
and tangential of pine wood that has been soaked
in water. Mount in dilute glycerine and study
with A A 2 and D 2.
Observe in the transverse section :

1. The annual rings.

Compare the two edges of a ring.

2. The thick-walled pitted tracheids.

3. The narrow medullary rays.

Make a diagram with AA% showing the relation of

the autumn to the spring ivood, and of the wood

to the medullary rays.
With D 2 sketch accurately a small part of the


In the tangential section observe :

1. The tracheids : their form, their arrangement,

and the pits in their walls.

2. The medullary rays.

Make a diagram showing the relation of tracheids

and medullary rays.
Sketch accurately with DZ a small part of tht


Observe in the radial section :



1. The tracheids. Why is a larger number of

pits visible in this section ?

2. The medullary rays.

Make a diagram shoiving tlie relation of tracheids

and medullary rays.
Sketch a few tracheids much enlarged.

From what has been seen in the three sec-
tions describe the shape of a medullary

II. Angiosperm.
A. Dicotyledon.

Ampelopsis. Prepared transverse section of
entire, young stem. Study with AA 2 and D 2.
AA 2. Observe :

1. Epidermis, one cell-row in thickness.

2. Cork (subepidermis) consisting of several

layers of flattened cells.

3. Cortical parenchyma.

4. Fibrovascular bundles.

5. Pith.

6. Medullary rays.

Which tissues have cell-contents ?

Cut a section from fresh material and see

which tissues contain chlorophyll.
D 2. In the fibrovascular bundle observe the

cambium layer dividing the bundle into

an inner part (xylem) and an outer part



Xylem, consisting of :

7. Large vessels or tracheae.

8. Tracheids, smaller in cross-section than the


9. Wood parenchyma (?). Thin-walled cells with

Phloem, consisting of :

10. Sieve-tubes, thin-walled and in some places

showing the perforated ends of the cells.

11. Bast-cells, thick-walled.

Sketch accurately a feiv cells of each kind in their

relation to one another.
B. Monocotyledon.

Observe with the naked eye the cut end of a stem
of Indian corn. Note :

1. The firm outer layer (epidermis and sub-


2. The fundamental parenchyma.

3. The isolated fibrovascular bundles.

Make thin cross-sections through the outer part of
the stem. Mount in dilute glycerine and study
ivith A A 2 and D 2.
Observe in the bundles :

4. The two large pitted tracheids.

5. The smaller, spiral and annular vessels (one

or more) between the tracheids and nearer
the centre of the stem. In many instances
the cells immediately surrounding these


vessels have disappeared, leaving an irreg-
ular space.
6. The thin-walled phloem on the side opposite

the vessels.

The prosenchyma forming the outer part of
the bundle does not belong to the bundle
itself. It is a bundle-sheath of modified
fundamental tissue.


Lay in water on a slide the root of a young mus-
tard-seedling grown in sawdust. Cover and ex
amine with AA 2.

1. Find the region in which root-hairs are


2. Moisten a piece of blue litmus-paper and

touch it to the root of a fresh specimen.
Record the result.

3. Examine the root-cap of Pontederia or of

Sketch under AA 2.


Winter buds of elder or of horse-chestnut.

I. Sketch the ~bud.

II. Take off the bud-scales and the undeveloped leaves

in regular order ', beginning with the outermost.
Notice the way in which they overlap.


III. Compare as to texture the outer scales with

what is inside. Suggest a reason for the
difference. What other means are there for
the same purpose ? (Make a note of the

IV. Compare a closed bud with others * in different

stages of unfolding. Make a note of what is


I. Strip off some of the epidermis from a hyacinth-leaf.

Mount in water and examine ivith AA% and D 2.
Observe :

1. The elongated cells of the epidermis without

chlorophyll. Compare with the epidermis
of the fern.

2. The stomata, each with two guard-cells con-

taining chlorophyll.
Sketch a few cells accurately (D 2).

II. Out a transverse section of the leaf of the india-

rubber tree (Ficus elastica). Mount in water.
Draw accurately.

Beginning with the upper surface find :
1. The upper epidermis, consisting of several

* Buds in different stages of opening can be obtained at any
time during the winter by keeping cut stems in water for a few
weeks. Flowering branches with the flower in different stages
of unfolding should be preserved in alcohol from the previous


layers of thick-walled cells without chloro-
phyll. Compare with the epidermis of the

2. Elongated cells closely packed together, with

their long diameter at right angles to the
surface of the leaf, the palisade tissue, con-
taining many chlorophyll-bodies.

3. Other cells containing chlorophyll, somewhat

irregular in shape and loosely arranged,
so that between them are large open
spaces, intercellular spaces.

4. The veins, fibrovascular bundles, cut trans-

versely or obliquely.

5. The lower epidermis, much like the upper,

but with stomata at intervals.
What is the relation between the position of
the stomata and the intercellular spaces ?


I. The General Structure.

(a) Borne on a short stalk (pedicel).
(6) Composed of four rows or whorls of

1. The external green calyx.

2. Inside the calyx the corolla, the most conspic-

uous part of the flower.

3. Inside the corolla the stamens.


4. Inside the stamens and forming the middle
of the flower, the pistil.

II. The Calyx.

Five green-pointed sepals attached around the
outer edge of the receptacle (expanded end
of flower-stalk).
Remove two sepals. Sketch.

III. The Corolla.

Consisting of five brightly colored parts,
petals. Observe that their insertion on
the receptacle alternates with that of the

Remove two or three petals. Sketch.
IY. The Stamens.

Ten in number, each consisting of a stalk-
like part, the filament, terminated by a
small expanded part, the anther The
filaments are united along part of their
length. The anther consists of two lobes
or thecae, and a very narrow connective.
Sketch a stamen.

Tease out an antlier in water and examine with

Numerous pollen-grains will be found.

Y. The pistil is surrounded by a tube formed by
the united filaments of the stamens. Take
the stamens off carefully. The lower two
thirds of the pistil is stout and green. The


upper third is slender and five-cleft at the
top (stigmas). The ovary is deeply lobed.
Make a transverse section through the ovary.

How many chambers has the ovary? Where

are the ovules attached ? Sketch.
VI. Make a diagrammatic sketch of the flower in
longitudinal section, showing the relative
position of all its parts.
Make a diagram of the transverse section of the


In like manner examine, sketch, and make
diagrams of the violet, of a papilionaceous
flower, and of a flower of the lily or of the
amaryllis family, following in each case
the order observed for the geranium, and
noting the differences.

For description of irregular parts, etc., the
student is referred to Gray's " Manual of
Botany," under Violacese, Leguminosse,
Liliacese, Amaryllidacese ; and to Miiller,
"The Fertilization of Flowers," under Vio-
lariese, Leguminosse, Liliacese, and Ama-


Mount pollen-grains of narcissus or of daffo-
dil in a 5 per cent, solution of cane-sugar in


water, and of pansy or of violet in a 30 per
cent, solution. Support the cover-glass.
Examine at once, first with the low and then
with the high power. Look for the nuclei.
Examine at the end of an hour, and again
after another hour.
Sketch different stages.


Examine seeds of the bean, of the pea, of
buckwheat, of Indian corn, and of wheat
that have been softened in water. Ex-
amine also dry seeds of the castor -oil
I. Bean.

1. Observe on one side the oval spot (hilum) to

which the stalk (funiculus) that fastened the
seed to the pod was attached.

2. Find near the hilum a minute opening, the

micropyle. If the bean is slightly squeezed
a drop of liquid may be pressed out through
the opening.

Cut the seed-coats along the convex edge of
the bean, remove them, and examine their
inner surface for the internal opening of the

3. Find the chalaza the base of the nucellus

where the seed-coats blend with each other.


4. Split apart the cotyledons and observe the
radicle and the plumule lying between them.

What is the position of the radicle with refer-
ence to the micropyle ?

II. Pea.

Examine in the same way as the bean.

III. Castor-oil Bean.

Carefully take off the hard outer seed-coat and
then strip off the thin inner coat. Separate
the bean longitudinally into two parts. Exam-
ine with a hand-lens.

Find the plumule, the radicle, and the cotyle-
dons. Is there anything else present ? What
differences are observable between the castor-
oil bean and the common bean ?

IV. Buckwheat.

With a small scalpel take off the outer seed-
coat. Observe the thin, light-colored coat
beneath. Remove this carefully, and find the
parts enclosed by it. How do they compare
with the parts within the seed-coats of the
bean and pea ? And with Ifhose of the castor-
oil bean ?

V. Indian Corn.

1. How do the two sides of the grain differ

in appearance ? Sketch.

2. With a scalpel peel off the seed-coats.
Observe the yellow endosperm. Kemove this,


and find the organ of absorption (scutellum)
enclosing the rest of the embryo and in
close contact with the endosperm.
Dissect out the parts enclosed by the scutellum.
Observe :

(a) The radicle directed toward the small end

of the grain, and the root-sheath covering
its free end.

(b) The plumule at the opposite end of the

embryo. Its outer leaf is the cotyle-

(c) The caulicle, the attachment between the

scutellum and the rest of the embryo.
3. With a razor make a median longitudinal section
through the broad sides of a grain. Observe
on the cut surface :

(a) The tough outer membrane, composed of

the united coats of the fruit and the

(b) The endosperm, consisting of starch and

other food-materials.

(c) The embryo, with its organ of absorption,

the scutellum.

Sketch the section much enlarged.
YL Wheat,

Examine the seed entire, and then find the

parts of which it consists.



I. Pea.

Cut thin sections of the cotyledons. Mount
some in dilute glycerine and others in

1. In the glycerine preparations observe in each


(a) Large starch-grains.

(b) Small aleurone-grains.

(c) Very finely granulated substance.
Observe the intercellular spaces.

Sketch one or two cells with cell-contents.

2. Compare the glycerine-preparation with the

water preparation.

Add iodine to the glycerine preparation.
What is the effect ?

II. Bean.

Examine as Pea.

III. Wheat.

Cut thin sections at right angles to the seed- coat y
and mount them in dilute glycerine.
Observe :

(a) Just within the seed-coat a layer of rec-

tangular cells containing aleuTone-

(b) More centrally situated, cells containing

starch. Add iodine. What is the
effect ?
Sketch a few cells.


IV. Castor-oil Bean.

Gently remove the brittle seed- coat, separate the
cotyledons, and make very thin sections of
the endosperm.

Mount some in pure glycerine and some in
water. Put others into a drop of alcoholic
solution of eosin on a slide. After Jive
minutes remove the eosin with filter-paper,
add 50 per cent, alcohol and a drop of
glycerine, and put on a cover-glass.

1. Study first the glycerine preparation. Ob-

serve : large aleurone-grains containing
spherical bodies (globoids).

2. Compare the water preparation with the

glycerine preparation. What difference is
observable ?

Add iodine to the glycerine preparation.
What is the effect ?

3. In the stained preparation look for crystalloids

in the aleurone-grains.

I. Dicotyledons.
A. Observe in the earlier stages the way in which

the seedling breaks through the ground.
Examine and sketch different stages of each of the
following forms :

1. Pea.

2. Bean.


3. Buckwheat.

4. Mustard.

B. Comparison of different kinds of seedlings.

(After examining and sketching the second com-
pare it with the first. In like manner compare
the third with the first and second, and the
fourth with the first, second, and third.)

1. Compare the roots.

2. Has each a stem supporting the cotyledons

(hypocotyl) ?

3. Compare the cotyledons :

(a) In regard to form and size.

(b) What might be inferred as to their

function ?

4. Compare the cotyledons of the pea and of

the bean.

5. Compare the pea and the buckwheat as to the

time of appearance of the foliage leaves.
To what may the difference be due ?
II. Monocotyledons.

Observe and compare different stages of the
following forms :

1. Indian corn.

2. Wheat.

HI. Compare the seedlings studied in I. with those
in II.

1. Observe the number of cotyledons.

2. Compare their form with that of the foliage



3. Note the venation of the foliage leaves and

their arrangement on the stem.

4. What is the character of the root-system ?


I. Mount in water a duster of young leaves of Nitella.

Examine with AA 2 and D 2.
Observe :

1. The chlorophyll-grains arranged in rows.

2. The neutral zone, free from chlorophyll.

3. The current of protoplasm just below the

level of the chlorophyll-grains.
Diagram !

II. Mount in water one or more hairs from the filament

of the stamen of Tradescantia.

With AA 2 note the rosary-like appearance of
the hair. Study with the high power and see
the active circulation of currents of protoplasm
around and through the central vacuole,

Diagram !

I. Mount in water some pieces of Nitella leaves.

Note especially at the cut ends the chlorophyll-
granules containing highly refractive bodies

1. Draw some iodine solution under the cover-

glass. What parts are stained ?
Diagram !

2. Mount another specimen of Nitella and add


chloral-hydrate iodine. Watch a few min-
utes for the effect.


1. The tip of a young onion-root.*

Find and sketch seven or eight stages.

2. The testis of the lobster.f
Find the principal stages.


* Method of preparation : Cut off a quarter of an inch of the tip
of young roots of an onion growing in water in a hyacinth-
glass ; put them into Hermann's fluid in the dark for 48 hours ;
wash in running water 24 hours ; imbed in paraffine and stain on
the slide with Haidenhain's iron-hsematoxylin, leaving the sec-
tions in the haematoxylin solution overnight.

f Pieces of the testis a quarter of an inch long should be pre-
served and stained as the onion-root. In making the sections the
pieces of testis should be cut lengthwise.


For an economical use of material this order may
be observed :

For the first day's work follow sections I-III in-
clusive, and in YI the directions for exposing and
hardening the central nervous system. This frog
should then be put into formic aldehyde solution of
1 to 2 per cent., which is especially good for hard-
ening the nervous system. If the odor of the formic
aldehyde is unpleasant, the material may be rinsed
in dilute ammonia before being used.

Taking a fresh frog on the second day, work out
upon it the circulatory and urino-genital systems,
sections IY and Y. This frog should be kept in
Wickersheimer's fluid, which preserves it in good
condition for the study of muscles, etc.

After a few days the brain, etc., of the first frog
will have become sufficiently hardened, and the
work may proceed in regular sequence. The direc-
tions after YI may be worked out upon either frog,
as the material serves.

For this work on the frog it is sufficient to use a
water solution containing from 1 to 2 per cent, of
formic aldehyde. "Formalin" is properly a com-
mercial name for a 40 per cent, solution of formic



aldehyde in water, but is often used indiscrimi-
nately for solutions of various strengths.

I. External Characters.

1. The division of the frog into head, trunk, and


2. The skin: moist and smooth. Note its


Make short slits in several places and inflate the

3. The head : its shape.

(a) The eyes : each with two eyelids (are

they movable ?).

(b) The tympanic membranes; modified parts of

the skin covering the ears.

(c) The nostrils or anterior nares.

4. The limbs.

(a) The anterior limb is divided into three

regions : brachium, antibrachium, and
maims. The manus has four digits. In
the breeding season the first digit of the
male bears a swollen cushion.

(b) The posterior limb is divided into three

regions : femur, cms, and pes. The pes
has five digits connected by a web.

5. Identify all openings into the body.

6. Look at a living frog in an aquarium-jar with

a little water to see its position, its eyes,
etc., and its mode of breathing.

FROG. 97

Make an outline sketch of the dorsal aspect of the

II. The Buccal Cavity.

Open the mouth and note :

1. Its wide cavity ; the posterior part, the

pharynx, is continuous with the oesoph-

2. The teeth :

(a) On the upper jaw.

(b) On the roof of the mouth.

3. The posterior nares.

To find them, pass bristles into the anterior
nares and note the points of entrance into
the mouth-cavity.

4. The Eustachian recesses : a pair of lateral pro-

longations of the mouth-cavity. Pass a
bristle through the tympanum from the
outside and note the place of its entrance
into the mouth- cavity.

5. The tongue. Note its shape and its attach-

ment. Turn it forward to see :

6. The glottis : a longitudinal slit in the floor of

the mouth.
Pass a probe into it.

III. The Abdominal Viscera.

Lay the frog iipon its hack in a pan containing
wax, and fasten it down with pins through the
limbs. Cut through the skin along the median
ventral line, and make a transverse cut at


each end of the first. Turn the flaps of skin
outward and pin them down.
Observe :

1. On the skin near the shoulder the musculo-

cutaneous vein.

2. The body-wall, formed of muscles.

3. In the median ventral line the anterior ab-

dominal vein.

Put a double ligature on this by making a slit
on each side of the vein and tying two threads
around it near together. Raise the body -ic all
with forceps, and with scissors carefully con-
tinue the cut on the left side of the vein from
pelvis to sternum. Make a transverse cut
between the ligatures and extending across the
ventral aspect of the body.
Note the anterior abdominal vein passing
dorsally into the liver.

With scissors cut in the median line through the
sternum and other superficial parts, taking
care not to injure the parts beneath. Turn
each half outward and pin firmly .

4. Sketch the organs exposed to view and identify

them. {Remove the ovaries if they conceal
the other organs.)

(a) The heart.

(b) The liver : reddish brown and bilobed.

(c) The lungs.

FROG. 99

(d) The stomacli : lying partly beneath the

left lobe of the liver.

(e) The small intestine : a light-colored

slightly convoluted tube. It passes
posteriorly into the large intestine.
The terminal part of the large intestine
is the cloaca. Note the mesentery by

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Online LibraryHarriet RandolphLaboratory directions in general biology → online text (page 4 of 8)