Re: More on A.pellucida

Dear Keith,

Yes! The image is by Dr. Henri van Heurck. The image and des-
criptive details can be seen at
http://www.baertierchen.de/archiv.html ,
which is the site of the Baertierchen microscopist Martin Mach
of Munich, Germany.

Mr. Martin Mach gives Willliam B. Carpenter "The Microscope"
1891, as the source of this image of A. pellucida.

Actually William B. Carpenter's "The Microscope and its
Revelations" is a series of books with this title which contain
important work in the fields of microscopy. The mentioned volume
is edited by W.H. Dallinger, since W.Carpenter had died previous
to the publication of this volume.

The book mentioned by Mr. Mach can be found at the Google book
site under
http://books.google.com/books?vid=OCLC00999815&id=YIYAAAAAMAAJ&pg=RA1-PR10&l
pg=RA1-PR10&dq=William+carpenter++microscopy+1891#PRA1-PR21,M1
and may be downloaded as a pdf file without charge.

I shall briefly describe what I found giving the page numbers
which the reader can enter on the bottom of the pdf reader.
This will save time because the search function does not work
on this type of pdf file.

Choose p. 13 on the counter on the lowest line of the Adobe pdf reader
and you will see the Frontispiece. Fig. 5 of the frontispiece shows:
"Amphipleura pellucida x 1860 diams., by apochromatic 1/8 1.4 N.A.
illuminated by a very oblique pencil in one azimuth along the valve."

Choose p. 25 and you will get to read about Plate XI which contains
three images of A. pellucida at magnifications of 2000x, 3000x and
2600x. The description goes into very interesting details of what Dr.
van Heurck thought was the structure of the valves of this diatom.
The text is too extensive to reproduce here.

Unfortunately I could not find Plate XI in the Google pdf file. Only
Plate I seems to have been scanned.

There are additional descriptions and remarks regarding the microscopy
of A. pellucida. You will find them on pp. 90, 106, 116, 260 and 551,
again using the search function at the bottom of the Adobe reader.

Page 551 makes very interesting statements regarding the great varia-
bility of the structure of A. pellucida which can present with easily
resolved valve details or details which are extremely difficult to
resolve. Again I must refer to the original text. These statements,
if supported by modern data, may have an important bearing on the
ability to resolve this diatom into "dots" using light microscopy.

Dr. Gary Gaugler will most likely explore the variability of
A. pellucida using his FESEM. Mr. Klaus Kemp (UK) will supply
samples.

Finally I wish to point out that my image of A. pellucida (see
the link in my original post) was obtained using a magnification
of 250x (100x from the objective, 2.5x from the projection lens),
while Dr. von Heurck used magnifications of 1800x to 3000x.

GR.

"Keith Shaw" <knshaw100@xxxxxxxxxxx> wrote in message
news:d6KdnRyRmI1ZEyrYnZ2dnUVZ_s-rnZ2d@xxxxxxxxxxxxxx
I was incorrect re identification of the A.pellucida image referenced in a
previous post, i.e. it may have been by Neuhauss.

On going back over some old notes, it appears that this image is from
W.B.Carpenter's book "The Microscope and its Revelations" published in
1891. It is accredited to Prof. Van Heurck, a rather well known
microscopist!

This image most probably originated with Martin Mauch at :
www.baertierchen.de

Regardless, the definition of the dots within the right-hand section of
this mount is startling - in fact it's hard to believe.

It would be real interesting if anyone can dig out information on the
equipment and illumination technique used by Van Heurck.
My notes indicate a Zeiss objective (presumably 100x) with NA 1.4 - a very
nice piece of glass (hand ground) back in the 1890s.

-Keith




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