Bresser National Geographic Mode D'emploi page 14

lines. The fibres shine like silk and exhibit numerous swellings along the shaft of the
fibre. Silk is of animal origin and consists of solid fibres of smaller diameter than the
hollow vegetable fibres. Each silk fibre is smooth and even and has the appearance
of a small glass rod. Wool fibres are also of animal origin; the surface consists of
overlapping scales, which appear broken and wavy. If possible, compare wool fibres
from different weaving mills, and note the differences in the appearance of the fibres.
Experts can determine the country of origin of wool based on its appearance under
a microscope. Celanese is artificially manufactured by a long chemical process. All
Celanese fibres show hard, dark lines on a smooth, shining surface. The fibres crinkle
in the same way after drying. Observe the similarities and differences between the
different fibres.
8.3. Saltwater brine shrimps Accessories:
1. Brine shrimp eggs (23d)
2. Sea salt (23c)
CAREFUL!
These eggs are not fit for human consumption.
8.3.1. Winter eggs of Artemia salina
Artemia salina are species of brine shrimp typically found in salt lakes — bodies of water
with a higher salinity than even the ocean. During a drought, a salt lake can become a
hostile habitat for organisms, and entire populations of Artemia salina sometimes die
off. During drought conditions, to ensure that the species will repopulate the salt lake
when the drought ends, Artemia salina lay thick-shelled eggs called winter eggs that
can survive for up to ten years in a dormant state. Winter eggs can withstand heat, cold
and chemicals. These eggs hatch when favourable conditions return to their ambient
environment. The eggs provided (23d) are of this type.
8.3.2. Hatching winter eggs
To hatch the brine shrimps, create a solution with an appropriate salinity and tem-
perature. First, fill two containers with a half litre of freshwater each, and let them
both stand for about thirty hours. Next, pour half of the provided salt (23c) into one
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3. Hatchery (21)
4. Yeast (23a)
container and stir the solution until the salt dissolves. Pour some of this solution into
the hatchery (21). Place a few eggs close to the lid. Position the hatchery somewhere
with plenty of light but not in direct sunlight. The ambient temperature should ideally
hover around 25 °C. As water in the hatchery evaporates, gradually add freshwater
from the second container. After two to three days, the eggs will hatch brine shrimp
larvae, called nauplii.
8.3.3. Observing Artemia salina under a microscope
Using the pipette (20a), move some larvae from the container to a microscope slide for
examination. When viewing the larvae, you'll notice that they swim through the solu-
tion using hairlike limbs! Each day, examine a few more. You can even view the entire
hatchery under the microscope if you remove its lid. The larvae will mature in six to
ten weeks, depending on the temperature of the water. Soon, you will have an entire
generation of saltwater brine shrimps that reproduce frequently!
8.3.4. Feeding your Artemia salina
Feed your brine shrimps often to keep them alive. The best food is dry powdered yeast
(23a). Give them some every other day. Be careful not to overfeed them, as doing so
can cause the water to stagnate and poison the brine shrimps. If the water does begin
to stagnate (you'll see it darkening), transfer the brine shrimps to the fresh saline solu-
tion you have prepared earlier (see 8.3.2).
9. Smartphone holder
Attach the smartphone holder to the eyepiece.
The suction cups must be clean and free from dust and dirt. A slight moistening is help-
ful. Now press your smartphone on the retaining plate and make sure that it is properly
secured. As a backup, you should secure it with the enclosed rubber strap. Smartphones
with a rough surface will not hold as good as smartphones with a smooth surface.
Now start the Camera app.
The camera needs to rest just above the eyepiece. Center the smartphone exactly over
the eyepiece, so the image can be seen precisely centered on your screen.
In some cases you need to adjust with the zoom function to display the image fulls-
creen. A light shading at the edges is possible. Take the smartphone carefully off the
holder after use.