Tuesday, 2 July 2013

TEST OF FRESH WATER DIFFLUGIA SPECIES

 
TEST OF FRESH WATER DIFFLUGIA SPECIES FROM SWANAGE BAY
Test in Simple reflected light
 
Test in crossed Polars with Victorian  selenite plate 
 
 
 
(N.B.Another test)Polar with cossed polars no plate
 
 
 
 
Quite often one change leads to a complete change of direction. I have been aware of the deposition of Fresh Water tests of testate amoeba in Swanage bay for several years but have rather overlooked them as an object of interest.
 
After several years of Dry mounting I have moved over to aspects of Mounting in Canada Balsam. and this has enabled photography using traditional methods such as Bright field, Dark field, and photography of arenaceous tests of foraminifera in polarised light.
 
More recently I have tried polarised light not only at full extinction of direct light but also when using various Victorian selenite plates. These effects are rather unnatural looking and much less sharp  but never the less they are quite compelling. I include my first effort as the coloured image above. The less colourful one below is a test from several years ago shown for comparison.
 
The diversity comes from the external protective layer of particles bonded onto the internal bag of equally protective chitinous material.They are of various thickness each distinguished with its own colour dependant upon its structure and thickness.

Thursday, 13 December 2012

This Post has been added to explain the idea of moving over to the mounting of Forams in Canada Balsam
The mounting of Foraminifera in Canada Balsam without Pressure.

 Foraminifera tests are more usually mounted dry to enable more natural views of these small shell like creatures to be observed.

 Although More frequently Mounted dry, the mounting in Canada Balsam has surprising results. At the Turn of the centuary in 1900 Joseph Wright the clear leader of the Belfast “School” of Forams, discovered that Canada Balsam mounting improved the clarity of vision and was particulary lucid for arenaceous tests. He makes a clear statement in his account of the Foraminifera of  Rathlin Island.

QUOTE from THE IRISH NATUALIST VOL 11 in 1902  page211 from old copy
 I have since examined with transmitted light specimens mounted in
Canada balsam,  and by this means. I have been enabled to see most distinctly the arrangement of the chambers throughout the entire test. I have examined In this way about 150 from dredgings taken off the Irish coast, including These Rathlin specimens, with a large number of fossil specimens from the Chalk of Co, Antrim; also the only perfect specimen, which I had of the variety fistulosa, Brady, from Raine Island Torres Straits 166 fathoms. In all Cases both the recent and fossil specimens when perfect had the early chambers arranged in a spiral manner.  Further research since 1888 hasTherefore confirmed me in my belief that this species  is truly a Spiroplectaand not a Textularia.

End of Quote

However those species constructed of crystalline calcite do become quite transparent when mounted in Canada balsam. The full beauty of the three dimensional spiral then becomes both evident and optically enhanced. The tests must be much cleaner than normally used for dry mounting and up to three days immersion in an open vessel of hydrogen peroxide may be required followed by washing in a fine sieve of pure water. The initial problem however, is ridding the mount of air bubbles before mounting commences. The tests may be laid as a small central strew or equally well they may be laid in a geometric or taxonomic array, depending upon the quality of material available. The tests can be secured to the glass with the Gum tragacanth more traditionally used for dry mounting and when dry, the slides can be immersed in toluene overnight in a Coplin Jar half filled with the solvent. Quite often vacuoles of air are trapped and unable to escape from the natural apertures within the test, so before mounting, the  need to be examined under the microscope. Species of the Lagena genus only have one small aperture so the slide may need to be inverted several times over two to three days. When the expulsion of air is complete, the slide can be laid on a hot plate and two drops of Canada balsam applied with a pipette and a coverslip laid. Since the tests are quite thick and brittle compared to other micro-organisms the slip must be applied without pressure and the simplest and best support is the use of three peripheral disks of around 0.5mm thickness 1.5mm diameter. The disks should be bonded to the coverslip before mounting using glass bond in sunlight followed by washing in toluene and drying with paper tissue before use. The cutting tool for these is flat nosed pliers drilled out for a piston on one side and a complimentary hole on the other These tools are actually available for the amateur Jewellery trade. Any burrs may be rubbed down on fine emery paper. Suitable brass or aluminium sheet from model shops can be purchased in various thicknesses but having been produced in the USA the measurements then tend to be imperial rather than metric. A vernier gauge is also a useful tool for this work of course. The space afforded by the three small discs also enables spontaneous bubbles to escape quite freely during the drying process. After several days of hardening the surplus balsam can be scraped away with a scalpel and the work can be ringed and protected with black shellac in alcohol and dried. Suitable labelling may then be applied. BD DEC 2012

Friday, 9 September 2011

The Two Images today Radiolaria from Barbados 9/9/11

Wednesday, 13 April 2011

A Successful Victorian Method of Mounting Radiolaria.

An Old Method of Mounting Radiolaria


Sometimes we use our own methods of mounting things that are perfectly satisfactory but occasionally when reading through old literature from the Victorian era we chance upon a method that really is excellent and much better than what we have. This is a description of just such a method from that age, which is equally suitable for use in dry mounting as in Canada Balsam.


Is begins with having a sieved washed sample of Radiolaria that has first been washed in acid and looks clean and bright in good light, before mounting.


Preparation is as with most things the key to success. Quality 3X1” glass slides need to be well washed and quality Gum Tragacanth as well as a ringing table is required.


Mountng in Resins such as Canada Balsam or Eukit.

The Gum Tragacanth solution must first be prepared . I use the lid of the gum jar as a painters pallet and add one very small portion of gum to a large pool of distilled water on the lid. When the gum is fully dissolved there must be no blobs of mucilage visible. If there are any blobs, use a pipette to suck them up and add more water, until nothing is visible in the fluid.

The clean 3X1” slide is placed on the ringing table and a little paintbrush is used to run a circular pool of gum water onto the centre of a rotating glass slide. Check that the circular disk of gum/water is stable, sometimes it prefers to run off into pools. Then perhaps the suface is contaminated and an alcoholic wipe might help.When the liquid is correct, dry it off with gentle heat until quite dry. One should be able to see a dried up but complete feint disk of dry gum . If it is too white and prominent, wash it off and try again with less gum or more water. Remember, that the dried up disk of gum will become the same diameter as the completed strew of Radiolaria.

Then make sure the slide is cool . Here a cold plate from a fridge might help, and breath on it. Ones breath should condense on the glass in droplets but the disk of gum will become slightly liquid, as it absorbs moisture. Then pour the shells from a Petri dish onto the central disk quite thickly and then invert the slide smartly over the Petri dish so that most of the loose shells return to the dish. Tap the glass to make them fall. Then use the warmth of a lamp to dry the thing off fully and again invert the slide over the Petri dish so that the shells that landed on the liquefied gum remain, but those that landed on damp glass now fall, having dried out. One should now be looking a a clean disc of Radiolaria surrounded by clear glass. Make sure that the whole slide is dry by heating under a lamp.

Then a resin like Canada Balsam thinned with a little Xylene is dropped on the middle to help expel the air from the shells. Then place a drop of thicker Balsam or other resin over the shells and lower a cover slip.

This may seem to be quite a performance for a tiny circle of Radiolaria, but it will be worth the effort. The resin may then be dried off with heat in the usual way, and the slide labelled.

Dry Mounting

Dry Mounts may be constructed in a similar manner but first an aluminium ring must be cemented to the glass and a black background must be laid and dried . More care is needed in any heating or the paint may be damaged. The circle of gum-water can then be laid using the ringing table. When this is successful the same procedures can be followed but without the Canada Balsam or other resin of course. This same system can also be used to renovate a very old slide that has through the ravages of time become thoroughly unsuitable for use. The method itself was I know learned from a very old book but I am afraid that I have long forgotten the reference or the original author of the idea.

Image to follow next weekend, hopefully BD


Tuesday, 9 November 2010

Two Species of Lagena

At the moment I am trying to complete an illustrated booklet on the Foraminifera from my digital pictures and I have just been distracted by these two species of lagena. As usual with only the resouurces of an amateur I am not too sure about this pair. As usual Cushman always comes up with something but sadly the illustrations are never so good for certainty. Please click on the image for a larger image. Any help would be appreciated BD.

Wednesday, 11 August 2010

A look at a 15 cm cube of chalk

This is a photo of an average sized species of Foraminifera sieved from chalk at Ballard Down. A 0.01 mm grid has been superimposed on the image in order to enable measurements to be made.The thickness can be estimated from the quite globular chambers.Effectively the organism is actually somewhat wedge shaped;thicker at the top than the bottom.

Please click once on the image in order to enlarge it.





This entry is an effort to estimate the number of Foraminifera tests in a 15 cm cube of chalk from Ballard Down Dorset Uk.



I have always thought that such efforts were rather a waste of time, because there are so many variables when dealing with fossil material 95million years old. Never the less its really surprising what sort of a number one can come up with, but it is just these figures no matter how inaccurate, that engage and surprise the general public.How do we find an average when there are so many eroded tests to sample ?


I have just taken a typical surviving test mounted in a canada balsam strew that is neither too small nor too large by observation. The initial measurements were taken with a Beck eyepiece graticule graduated in parts of a mm. I shrank and expanded the image until it was exact according to my record through the microscope.
Since the chambers of the test are quite globular, I measured the radii of each chamber and calculated the volume of each, using the formula (Radius cubed times PI times 4/3) ; the formula for the volume of a single globe. The results were then added together. My selected "average" test made 0.00044107 cu mm which is pretty small .

This was then divided into the volume of the 15cm block cube which is hopefully 3,375,000 cubic mm. The result is rather nicely 7,651,846,645 which is fascinatingly enough very nearly the human population on Earth not so long ago. I think we are currently way past this figure and well over the 8 billion. This means that the calculation for the whole of Ballard Down would need a considerable amount of paper, and my old computer would certainly blow a fuse in the process.
When I consider the effect of potential inaccuracies on this figure it can more probably become greater than smaller.

I fully appreciate that numerous other and perhaps better methods can be used to arrive at a figure. I tried several alternatives but came back to the above with all its faults. BD.

Sunday, 14 February 2010

A Question concerning the point of the needle answered

On 14 February 2010 09:32, wrote:
This refers to an article of mine in Micscape UK QV on a mounted needle.

Hi ............
Yes I knew it!!!!!!!!.............. I should have spent more time writing about the point.

that was the really the point of the aticle I suppose.!!!................
I have to write that at first I could not find a tube that was 1mm external so I used 1.5mm diam. and had to shape the point by rotating it when it just protruded from my mark one version . I used a combination of a fine triangular file and very fine sandpaper to make a blunt point of about 0.3mm diam. at the end but the very end was flat and burnished flat and then painted with Matt black.
The relatively. large forams like Elphidium I glued on the round end with water based Gum tragacanth so that any part of the periphery could be imaged. by rotation .====Then I decided that a flat platform was also a good stage for angular shots of apertures .so I filed one side flat to create a flat stage 2mm long which bit into the end of the cylinder to a width of 0.3mm. I had to buy a brass vernier measure .
When I found my 1mm external hollow brass tube in Holland the diameter of the insert was 0.3mm and that was the right size without treatment except when I wanted the inclined stage. All the measurements were based on my wanting to look at the Foraminifera tests. and in particular those of +_ 500um diam.

So briefly Gumming with Gum Tragacanth on the end of the 0.3mm insert rod is how I now do it.

Centralisation on the end so would be trial and error whilst under the microscope as the tests are drying off..


Its up to you folk to develop it. I can see that some with a large(ThicK) mechanical finger on thir stage (ie the Clip)may need another slide glued underneath but that is not a problem. Also for reflected light only then a layer of paint underneath might look neater and avoid little glares!.

Also Please read info on the supply of 1mm hollow tubes
NOTE for integration into the text or at the end.

A SUPPLY OF 1MM HOLLOW BRASS TUBES.
At first I could not find any tube less than 1.5mm in diameter in the
UK. I had to use thicker glass up to 1.5mm but it
was much more difficut to cut neatly.

Even on line scanning on US sites, I found nothing; they still seem to
be using imperial measure anyway. Then I began to look at the EU and
sure enough there was the 1mm I was looking for on a Dutch site for
hobbyists.

http://www.plasticmodelbouw.nl/contact


The internal hole was 0.3mm which was just right. A pack of several
tubes was less than £10 with postage and took only 3 days BD.
Best wishes Brian Darnton. Swanage UK