Lugol vs. Melzers solution - hemiamyloidity

[mollisia]

Hello,

because of a discussion in another thread I want to show for those who are interested in examining inoperculate ascomycetes the possible differences when using Lugol instead of Melzer.
It was H.O. BARAL who discovered, that a certain amount of inoperculate species (appr. 20%!) show a red porus reaction in Lugols solution, when prepared in a water mount or direactly in Lugol. This red reaction is supressed by the chloral hydrate that in Melzers solution is encluded and by the too strong iodine and iodide concentration. Moreover, when pretreated with KOH (as one usually does with herbarium species), the reaction will never be red, but always blue, either in Lugol or in Melzer.

Here is a plate from Zottos conference about vital taxonomy. I will show some more in another thread.
The plate shows Hypoxylon serpens, which is easily determined (at least as agg.) by the red porus reaction in Lugols/Barals solution. No other european Hypoxylon known up to now has a red reaction. If you use Melzers it will be unseen and you will think it to be negative. If you pretreat with KOH (herbarium specimens e.g.!), you will always see a blue reaction instead of the red one!



I think it is obviouse, that it DOES make a difference whether you use Lugol insted of Melzers and I can only strongly recommend those working with these fungi that they should use Lugols or better Barals solution. Lugols is sometimes too weak.

Barals: 3g potassium iodide + 1g Iodine crystals solved in 100ml destilled water.
Lugols: 2g potassium iodide + 1g Iodine crystals solved in 300ml destilled water.
Melzers: 1.5g potassium iodide + 0.5g Iodine crystals + 22g chloral hydrate solved in 20ml destilled water.

best regards,
Andreas

[fairplay]

The law in obtaining certain chemicals may be different in this country.

Does anybody know if and where you can obtain these chemicals ?

Thanks again Andreas, I try to keep the chemicals I use to a minimum, as they tend to hang around the house without ever being used.
When the mixture is made up, what sort of life expectancy does it have ?

Neil.

[Ditiola]

at www.brunelmicroscopes.co.uk/solvents.html

they have Lugols Iodine £7.83 per 250ml

Peter

[fairplay]

A friend in Norfolk who is a doctor may be able to help out.

Better take the plunge I guess.

Neil.

[SheffieldLass]

Thanks Andreas for that useful info. I've copied it for future reference.

Lugol's isn't (or wasn't) too difficult to obtain. It is used by pigeon fanciers as a dietary supplement for their pigeons, and is fairly cheap through their suppliers. Though I've just done a check with one supplier and it is out of stock, which might mean it has been banned ....

Melzer's is very difficult to get hold of.

Melanie

[mollisia]

Originally Posted by SheffieldLass

Melzer's is very difficult to get hold of.

Melanie

Hi Mel,

why? What is the problem with that? Do you think because of the chloral hydrate?

I can send you a litre of it (or more) or if you like to 100 bottles of 10 ml each to a good price

Melzers, Lugols and Barals solutions are stable and can be kept over years without problems.

best regards,
Andreas

[SheffieldLass]

Originally Posted by mollisia

Hi Mel,

why? What is the problem with that? Do you think because of the chloral hydrate?

I can send you a litre of it (or more) or if you like to 100 bottles of 10 ml each to a good price

Melzers, Lugols and Barals solutions are stable and can be kept over years without problems.

best regards,
Andreas

Yes, because of the chloral hydrate. Even Sheffield University doesn't have it these days. I may well take you up on that offer.

cheers
Melanie

[mollisia]

Hello Melanie,

Originally Posted by SheffieldLass

Yes, because of the chloral hydrate. Even Sheffield University doesn't have it these days.

I could understand that if it would be chloral hydrate only. But Melzers is ready prepared in one bottle, with the chloral hydrate already mixed in. So what is the problem?

I may well take you up on that offer.

You are welcome!

best regards,
Andreas

[Ditiola]

Hi
I believe there is at least one mycological organisation that offers Melzers with and without Chloral hydrate for sale to its members.

From this I presume it works OK without the Chloral Hydrate.

I have found that Lugols Iodine is OK for the amyloid reaction but does not show the brown dextrinoid reaction like Mezers does.

Peter