Puttin' on the brakes

[Dembowski]

I've got a new-timer question for you folks. I've seen many comments made about how quick this protozoa is, or how tough it is to get a shot of that one ... and yet I don't recall anybody mentioning stuff like methyl cellulose to slow them down.

Am I missing something? Is it not so wise to use it, or perhaps I should take it for granted that everyone does?

[gpmatthews]

I sometimes use hydroxypropylmethyl cellulose 6 cps (HPMC). One technique I have used is to catch the organism I want to observe with a stretched Pasteur pipette and place it in a drop of water on a microscope slide. I then sprinkle it with a little HPMC. Wait for it to disperse, and then place on a coverslip in the usual manner. One advantage with using a low viscosity HPMC is that it disperses in cold water readily. Higher viscosity grade cellulose derivatives(like those used in wallpaper paste) can form lumps of gel and do not disperse so readily.

You can also slow down many organisms with a little local anaesthetic - try a drop from a lidocaine throat spray. Very good for immobilising copepods, ostracods and cladocera as well as many other small animals.

[piotr]

Bill,

I use Detain from WARD'S Natural Science to slow down the protozoa. It's very effective.

But sometimes I like the challenge of catching a fast swimmer!