A look at an old slide
by Mike Samworth
A friend quite recently gave me some dusty prepared slides.
Most of these were quite uninteresting slides, either fairly
standard histological material for school use or were slides that
had not lasted too well, despite only being twenty or thirty
years old. However, there was one that immediately took my eye,
and I put it to one side for looking at later. As often happens,
the "later" is often VERY much later!
The slide has just one label on it, a rather fancy affair
with the following hand-written on it; Polycistina from Barbados.
The following scan shows the label;
A slide of polycistina from the rocks of
Barbados was a very popular object with Victorian microscopists,
being considered one of the most beautiful objects for study.
According to the author of one Victorian book, people have been
tempted to purchase microscopes from having seen for the first
time, a collection of these matchless structures. They are
actually fossils, being the homes or skeletons of Radiolaria.
During the 'Challenger' expedition vast numbers of Radiolaria
were found in the ocean surface dredgings. Within a framework of
only a hundreth of an inch in diameter there may be dozens of
spines radiating from the centre, often beautifully sculptured
and branched. Others appear as spiny balls made up of an
elaborate latticework of glassy texture. The photomicrograph
below shows how much like Chinese ivory carvings some of these
Polycistina from Barbados.
Radiolaria are all marine; most of them live near the surface
in tropical seas, and their skeletons sink to the bottom in what
is sometimes referred to as a raining down of material. They can
form extensive deposits and their study is of great importance to
the oil industry in particular.
This old slide is a nice one that I enjoy looking at. I do not
have any idea whatsoever who made it, or indeed how long ago, but
it is in quite good condition, and testament to the skills of
Photomicrograph by Mike Samworth.
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