Windowsill dipping

gpmatthews · Post by **gpmatthews** » Sun Mar 11, 2012 11:53 am

A while ago I left a sample from my local nature reserve sitting on the widowsill. I had a quick look at it this afternoon - loads of creatures!

Here is a selection:

Cilate - Nassulidae?

Rotifer - species?

Rotifer - Lepadella sp

Rotifer - Encentrum sp

Microscope - Zeiss Standard
Ocular: Zeiss KPL-W 10/18
Objective: Leitz 40/0.7 NPL Fluotar ICT (except second image - Leitz 25/0.55 NPL Fluotar ICT)
Substage: Leitz ICT 0.9 NA

Bruce Taylor · Post by **Bruce Taylor** » Sun Mar 11, 2012 1:24 pm

Nice. The ciliate is probably Nassulopsis elongata (note the cluster of pigmented granules just ahead of the nasse).

gpmatthews · Post by **gpmatthews** » Sun Mar 11, 2012 2:48 pm

Thanks Bruce - very helpful.

Just to take my tally of images up to 6 for today, here is another Lepadella:

Cactusdave · Post by **Cactusdave** » Mon Mar 12, 2012 12:45 am

Nice images, especially the Encentrum rotifer.

gpmatthews · Post by **gpmatthews** » Sun Mar 18, 2012 3:05 pm

I'm not convinced about he "Encentrum sp" - may well not be, but here is a stereo pair of a smaller specimen seen from the side. It appears to be a grazing species,that creeps rather than swims.

The specimen was anaesthetised with dilute lidocaine hydrochloride solution run along the edge of the coverslip and then left to relax for a couple of hours (the lidocaine was in a throat spray containing mannitol which tends to seal the edges of the coverslip and prevent evaporation). Other species of rotifer on the slide did not relax, but this one did fairly well.

Wim van Egmond · Post by **Wim van Egmond** » Mon Mar 19, 2012 12:36 am

Your DIC set works very well, Graham. I am not sure of DIC is the best technique for making stereo images because of the highlight and shadows. But it is nice to see a rotifer in 3D. I hope you will be able to make more. The narcotizing technique seems to work well. I once heard that in the Victorian days they used Cocaine to relax rotifers. A pity that they removed it from Coca cola. Otherwise that would be the trick!

One little comment. The second and third image are a bit dark. I think they would look better of they were a bit lighter. Do you shoot in raw?

Wim

rjlittlefield · Post by **rjlittlefield** » Mon Mar 19, 2012 12:56 am

Wim van Egmond wrote:I am not sure of DIC is the best technique for making stereo images because of the highlight and shadows.

I agree the stereo is problematic. But I think the problem is just that DIC finds detail everywhere at every level within the subject. When the stereo is assembled, all those details produce a confusing "cloud" of features rather than becoming a relatively simple surface like the shell of a diatom. In the stereo rotifer, I get a clear perception of debris clustered in two planes, one in front and one behind the rotifer, but the rotifer itself makes no immediate sense to my eyes.

--Rik

gpmatthews · Post by **gpmatthews** » Mon Mar 19, 2012 1:59 am

I too intitially had problems with the stereo, but found that it improved with studying and was pleased with how it enabled me to see the disposition of the cilia. There is, however, a lot of detail that is potentially confusing and a layer of bacteria on underside of the coverslip overlays the rotifer which doesn't help

I also noted the use of cocaine by the Victorians, also eucaine and more recently bupivacaine. Some have also used dilute alcohol, but everything I have tried to date tends to make most rotifers contract and stay that way. This was the only one that was in any way relaxed.

For stacks I tend to shoot with jpg, just because of the processing time. I find DIC a bit of a problem in terms of extremes of contrast - quite often you get very bright highlights but much darker background and shadows.

Cactusdave · Post by **Cactusdave** » Mon Mar 19, 2012 3:08 am

I agree that 'hard' lighting can be a real problem with DIC. It may be more so in older DIC implementations as Rogelio doesn't seem to have this problem, or at least if he has he seems to have more control over it. This may also be so of the PZO DIC condenser which seems to offer a lot of control. With my Diaphot DIC I have found that playing with all the possible factors, condenser height, condenser diaphragm aperture, setting of the lambda compensator and rotation of the recombining Wollaston prism, and carefully optimising each, gives the best chance of getting even and not harsh DIC illumination. On an old, and much used by previous owners, DIC setup like mine on my Diaphot, the variability of DIC illumination is a constant battle.

Mitch640 · Post by **Mitch640** » Mon Mar 19, 2012 12:21 pm

Number 3 and 4 look like they have critter cams on them. It's like being there, floating above them.

gpmatthews · Post by **gpmatthews** » Sat Mar 24, 2012 3:55 am

- an update.

I discussed the "Encentrum" image with Eric Hollowday, our rotifer expert at the Quekett, and he tells me that this is in fact a Lindia species. This is confirmed by the trophi which can also be seen fairly clearly in the image.