Bresser 5116200, Instruction Manual

Page: 18 / 24

18
8. Experiments
If you made yourself familiar with the
microscope already, you can accomplish
the following experiments and observe the
results under your microscope.
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 magazines
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 fibres
Objects and accessories:
1. Threads of different textiles: Cotton, line,
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 staples 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 staples consist
primary of long, collapsed tubes. Linen fibres
are also 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 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 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 ripple
themselves/crinkle after drying in the same
condition. Observe the thing in common and
differences. 8.3. Salt water prawns
Accessories:
1. Prawn eggs (Fig 2, 25d)
2. Sea salt (Fig 2, 25c)
3. Prawn breeding plant (Fig 2, 23)
4. Yeast (Fig 2, 25a)
CAREFUL!
Eggs and prawns are not fit
for human consumption.
8.3.1 The lifecycle of the saltwater prawn
The saltwater prawn 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 prawns are all
female. Under unusual circumstances such
as when a swamp is drained the eggs may
produce male prawns. 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 and can survive the swamp or
lake drying out causing the death of the entire
prawn population for up to a decade in a form
of hibernation. The eggs hatch once the right
ambient conditions again obtain. The eggs
supplied (Fig 2, 25d) are of this type.