Volvox

[Charles Krebs]

Olympus BHS, 20/46 S Plan Achromat, 1.67 NFK photoeyepiece, darkfield illumination, Canon DSLR, Electronic flash.



Olympus BHS, 60/1.40 S Plan Apo, 1.67 NFK photoeyepiece, DIC illumination, Canon DSLR, Electronic flash.



Olympus BHS, 100/1.40 S Plan Apo, 1.67 NFK photoeyepiece, darkfield illumination, Canon DSLR, Electronic flash.

[rjlittlefield]

Lovely images, but what grabs my attention (you might have guessed!) is a detail of the cell structure shown by the DIC image.

It seems that every cell has two little "nipples" on it. Most but not all of the cells have a single flagellum coming from one of the nipples, with the other one empty. Some cells have no visible flagellum, even though two nipples are clear. A few cells appear to have two flagella, but on closer study I'm pretty sure that's an illusion caused by the way a flagellum from one cell just happens to line up with an empty nipple on another cell.

What can you tell me about these structures I've called "nipples"?

--Rik

[ABEL]

Hello Charlie

I have never found a volvox and nice photos

[Pau]

Hi Charles,
Very nice shots as always.
In the last one you say drakfield and 100/1.40 objective. Can you explain your setup?. Did you have reduced de AN of the objective? ( I was convinced that darkfield was not possible at such high NA, but several of my previous assumptions have changed after 2 years learning in this forum)

[RogelioMoreno]

Charles,

Excellent images!

I would like to see the DIC image with colors.

Rogelio

[Charles Krebs]

Thanks all.

Rogelio... I edited the post and put the color DIC version in instead of the grayscale (I was too lazy last night to play with the raw file so I just converted the jpg to b+w... poorly)

Pau.. I used a Zeiss darkfield condenser (high NA, oil type). This give a NA 1.2-1.4 ring of illumination for darkfield. My 100/1.40 S Plan Apo does have an aperture control. I need to reduce the aperture with this control so that it is a little less than NA 1.2. I do like the "look" of high NA darkfield sometimes. But it is very unpredictable how subjects that have great depth will appear. This is because of the brightly illuminated out of focus "clouds" that appear around the focused part of the subject.

Rik... below is a (oversharpened!) full pixel crop from the above DIC image. You can see the details better. Frankly I've never looked at the flagella that closely before. According to these references there should be two per cell... :
http://starcentral.mbl.edu/microscope/p ... mageid=940
http://www.jochemnet.de/fiu/bot4404/BOT4404_28.html

... but I'm only seeing one in this crop

[Pau]

Pau.. I used a Zeiss darkfield condenser (high NA, oil type). This give a NA 1.2-1.4 ring of illumination for darkfield. My 100/1.40 S Plan Apo does have an aperture control. I need to reduce the aperture with this control so that it is a little less than NA 1.2.

Thank you Charles,
the objective aperture control does explain all. I'm unable to obtain good darkfileld whith the same condenser (Zeiss ultra darkfield 1.2/1.4) and the Leitz NPL Fluotar 100/1.32 both oiled, but because it's a phase objective I doubted if it would be posible.

[Ken Ramos]

You know Charlie, I wish you would get an SEM. I would love to get a look at those microtubules. Wonderful post as usual.

[Jean-marc]

Hi Charles,

I never saw Volvox, but your photo is beautiful, and the subject is very interesting.
Where have you found it ?

JM

[Charles Krebs]

Jean-marc

Where have you found it ?

I find it (not too often) in a small pond and at the marshy edges of a lake near my home. (Not on the bottom but in the water and among other collected vegetatation.)