Trees under the microscope

[daltontrees]

Cheers. I'm off now to try and make a microtome out of nuts bolts and washers. Then if that works I'll make a thin section slide.

 

For anyone that doesn't know, a microtome is a machine that holds a sample (like a twig or a leaf or a bud) while you take very very thin see-through slices off it.

[daltontrees]

OK the makeshift microtome is made, but first I am going to put up some pictures of a real microtome. The one I have is about as basic as they come, real lab ones can cost £thousands.

 

This one can be clamped onto a table edge. It is basically a block of metal with a smooth top surfaces and a piston up the middle thaty can be advanced by means of the gnarled screw at the bottom. One twist on the screw produces a click and advances the piston a tiny amount, 10 microns. A micron is 1/1000 of a millimetre. A typical biological sample will be thin-sectioned after about 5 clicks, i.e. 50 microns which is about 0.05mm.

 

The sample is put in the top and the space around it is filled slowly with molten parrafin wax. The pictures show the start of the process for a piece of Poinsetta leaf. I am warming the wax part of a tealight candle on a spoon over the gas cooker.

[daltontrees]

Emmm... here's the spoon. bit

[daltontrees]

I had picked up a Lime twig in the street and thought it would be nice to do a few sections of the buds, longways and across-ways. The pictures show the buds being laid and stood up in the softened wax, then set in a solid lump of wax. Aftyer that it is necessary to advance the microtome a few clicks then draw a (very very sharp) razor across the top of the metal block. This takes a thin slice of wax and sample off. The wax usually falls away and the sample can be floated onto a new glass slide for viewing.

[Gary Prentice]

Is there any advantage using the cut throat over a normal razor blade? Most of the microtomes I've looked at seem to use the cut throat but then I'd imagine you'd have to learn to sharpen it.

[daltontrees]

Is there any advantage using the cut throat over a normal razor blade? Most of the microtomes I've looked at seem to use the cut throat but then I'd imagine you'd have to learn to sharpen it.

 

An ordinary razor will flex during the cut and will either ride over the sample or will submarine into the wax and give you an overly thick slice.

 

I would sharpen the cuthroat razor every 10 cuts or so. On a very fine grained grindstone in oil.

[daltontrees]

There's a really lovely slide for sale on ebay just now

 

ANTIQUE MICROSCOPE SLIDE. FOSSIL WOOD. LOUGH NEAGH, IRELAND. CUPRESSINOXYLON | eBay

 

it's a thin section of a fossil tree from northern ireland. It has still got much of the cell and ring structure visible, but the original organic material has been replaced with minerals. Some of the photographs on ebay have been taken in cross polarised light (see my earlier postings about this), with resultant interference colours.

[sloth]

May be of interest to someone...

http://www.summerfieldbooks.com/the%2Dmicroscope%7E4125

 

Sent from my GT-I9100 using Arbtalk mobile app

[daltontrees]

Couple of pics of Neodiprion sertifer (European Pine Sawfly) caterpillars under the USB microscope last week.

[Gary Prentice]

So, microscope, immersion oil, 250 slides (forgot cover slips), pipettes, lens paper, single edged safety razors, cutting boards.... What else do I need?

 

Microtome, stains, USB camera..... Anything else?