Re: More on A.pellucida

Rene,

Well, thank you for your reply and the reference to the
Yahoo group.

I am aware of the long history surrounding the imaging
of A. pellucida and the many attempts, more or less success-
ful to resolve striae or dots.

What has been missing so far was a comparison of a good
light microscopy image with superb and quantitatively
precise SEM images. These were obtained by Dr. G. Gaugler
and presented in the current thread. These images are unique
in several respects: They show measurement of important
parameters on the frustules of A. pellucida, not only on one,
but on several specimens. This allows the comparison of
these values on samples of the SAME origin and of the
same size. It also shows a light microscope image of A. pel-
lucida from the SAME source and of comparable size.

I think this makes for very interesting reading for those inter-
ested in the subject and is not meant to be imply that others
have not obtained good pictures of A. pellucida. In fact I
do point to a very detailed image of A. pellucida by a link.

GR.

"rene" <renevanwezel@xxxxxxxxxxx> wrote in message
news:1169487124.952998.249010@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Discussion of KKemp material and imaging of Ap has been going on for
years on the yahoo microscope discussion group, you can find my images
overthere. It is similar to your result, but with an old microscope
with 15W Tungsten/420nm bluefilter, annular illumination with a
modified BF condenser and a 70 year old achromatic Beck 1.3 NA
objective.
Many others have done the same exercise with better results (then mine)
by playing with oblique illumination.
Indeed, lack of contrast is the bottleneck, caused by 'thin frustules'
(as KKemp calls it), ie little silicification between pores in the
striae. The (inter)striae themselves are heavily silicified bars,
therefore reasonably easy to image compared to the pores.

René.



.