Microscope Settings (Direct Light); Experiments (Transmitted Light) - Bresser BioDiscover DuoLux Mode D'emploi

specimens are examined the light from below goes through the
specimen, objective and eyepiece to the eye and is magnified en route
(direct light principle). Many small organisms of the water, plant parts
and finest animal components have now from nature these transpa-
rent characteristic, other ones
must be accordingly prepared. Is it that we make it by means of a
pre-treatment or penetration with suitable materials (media) transpa-
rent or thus that we cut finest wafers off of them (hand cut, MicroCut)
and these then examine. With these methods the following part will
us make familiar.
6.2 Producing a thin specimen slide
As already stated, specimens for microscopic observation should
always be sliced as thin as possible. A little wax or paraffin is needed
to achieve the best results. A candle can be used for the purpose. The
wax is put in a bowl and heated over a flame. The specimen is then
dipped several times in the liquid wax. The wax is finally allowed to
harden. Use a MicroCut (Fig. B 18) or knife/scalpel (careful!!!) to slice
the wax-coated specimen as thinly as possible. The slices are laid on
slides and covered with a covering glass.
6.3 Making your own specimens
Place the specimen on the slide and add a drop of distilled water
with a pipette (Fig. B 20) to the specimen (Fig. B I). Set a covering
glass vertically at the edge of the drop so that the water runs along
the glass edges (Fig. B II). Then slowly place the covering slide atop
the drop.
Note
The gum media provided (Fig. B 24) is used in making
permanent slides. Add it instead of distilled water. The
medium hardens and the specimen is then permanently
affixed to the slide.

7. Microscope settings (direct light)

You can adjust both upper and lower lighting individually or together
to optimally illuminate any specimen. The best results in the direct
light mode are achieved by combining the 5x eyepiece and the 4x
objective. Any other combination increases magnification but reduces
the field of visibility.

8. Experiments (transmitted light)

Once you´re familiar with the microscope you can try the following
experiments and view the results.
8.1 Newspaper print
Objects:
1. A small piece of paper from a newspaper with parts of a picture
and some letters,
2. a similar piece of paper from an illustrated magazine.
Use your microscope at the lowest magnification and use the
preparation of the daily paper. The letters seen are broken out, because
the newspaper is printed on raw, inferior paper. Letters of the maga-
zines appear smoother and more complete. The picture of the daily
paper consists of many small points, which appear somewhat dirty. The
pixels (raster points) of the magazine appear sharply.
8.2 Textile fibers
Objects and accessories:
1. Threads of different textiles: Cotton, linen, wool, silk, Celanese,
nylon etc.,
2. two needles.
Each thread is put on a glass slide and frayed with the help of the two
needles. The threads are dampened and covered with a cover glass.
The microscope is adjusted to a low magnification. Cotton fibres are
of vegetable origin and look under the microscope like a flat, turned
volume. The fibres are thicker and rounder at the edges than in the
centre. Cotton fibres consist primary of long, collapsed tubes. Linen
fibres are also of vegetable origin; they are round and run in straight
lines direction. The fibres shine like silk and exhibit countless swelling
at the fibre pipe. Silk is of animal origin and consists of solid fibres of
smaller diameter contrary to the hollow vegetable fibres. Each fibre
is smooth and even moderate and has the appearance of a small
glass rod. Wool fibres are also of animal origin; the surface consists
of overlapping cases, which appear broken and wavy. If it is possible,
compare wool fibres of different weaving mills. Consider thereby the
different appearance of the fibres. Experts can determine from it the
country of origin of wool. Celanese is, like already the name says,
artificially manufactured by a long chemical process. All fibres show
hard, dark lines on the smooth, shining surface. The fibres crinkle
after drying in the same condition. Observe the thing in common
and differences.
8.3 How does bread mould develop?
Object: An old piece of bread.
The spores of the kind of mould, which strike our bread, are to be
found everywhere in the atmosphere. Put bread on a slide and squirt
carefully some water on it. Moisten bread only, don´t wet it. Put the
whole into a container with a screw-type cap and place it into a
cabinet, into which only little light breaks in and which prevails it in a
warm temperature. Within a short time the black bread mould forms.
Regard the bread each day. At the first the mould shows up a white,
shining consistence. Take it on a slide to observe it. The material turns
out as a complicated thread mass, which forms the fungus body in its
whole. One calls the whole mycelium. Each thread is a hypha. Soon
some rhizoids arise, which embody the mould fungus with bread, in
order thereby to receive water and nutrients for the growth of the
mycelium. In the course of time the Rhizoid colours itself brownish.
Vertically over this group hyphae grow like long slim stacks, which
end in a tiny small, white ball. One calls the stack sporangiophores
(carrier of the sporcap), the ball is a sporangium or a sporcap. Soon
these balls accept a black color. Inside spores present mature. If now
the sporcap breaks open, then it sets the spors free, which step now
to air and infect other bread. With the naked eye you can recognize
mature the sporcaps as tiny black marks. They are scattered on
the mould fungus surface and give thus to the kind of mushroom its
name. There are however still different kinds of mould fungi. They can
be pink, red, blue or green. Manufacture yourselves preparations of all
stages of the bread mould.
8.4 Salt water shrimps
Accessories:
1. Yeast (Fig. B 23),
2. Gum media (Fig. B 24),
3. Sea salt (Fig. B 25),
4. Shrimp eggs (Fig. B 26),
5. Shrimp egg hatching plant (Fig. B 22).
8.4.1 The lifecycle of the saltwater shrimp
The saltwater shrimp or Artimia salina to scientists has an unusual
and interesting lifecycle. The female´s eggs are hatched without any
male shrimp having to fertilise them. The resultant baby shrimps
are all female. Under unusual conditions such as when a swamp is
drained the eggs may produce male shrimps. These males fertilise the
female´s eggs, resulting in a specific type of eggs. These are called
winter eggs and have a thick shell as protection. They´re pretty rugged
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