Boston Mycological Club

David Malloch's Lab Session: Secrets of the Deadly

by Jason Karakehian

Saturday, November 12, 2011 Step aside, PBS, with your Secrets of the Dead. Led by Canadian mycologist Dr. David Malloch, twenty BMC members diagnosed a mock mushroom poisoning case at Harvard's Farlow Herbarium microscopy lab. They were challenged to identify the remains of poisonous fungi so that medical personnel could administer the proper treatment for poison victims.

For our lab, Dr. Malloch had prepared a "mushroom stew" from Dinty Moore beef stew and several poisonous and non-poisonous mushrooms that he had collected and dried. Among the poisonous species were Cortinarius rubellus, Inocybe sp. and Russula emetica. This leftover stew was to be the evidence from a poisoning case.

Solids remain after straining off the stew's liquids. Solids remain after straining off the stew's liquids.

Teasing out the mushrooms from the rest of the stew, we made slides of gill tissue to see spores and other diagnostic microscopic characters like cystidia and sphaerocysts.

BMC members examine the spores and tissues in the cooked mushrooms to identify the fungus.BMC members examine the spores and tissues in the cooked mushrooms to identify the fungus.

Heads down at the lab. Heads down at the lab.

An experienced consultant for his regional poison control hotline and hospitals in New Brunswick, Dr. Malloch described the difficulties of identifying mushrooms from cooked leftovers or stomach contents.

Careful questioning can help to identify whether an alcohol-reactive mushroom, such as Coprinopsis atramentaria, was the culprit. Did the sickened victim eat mushrooms that were not cooked with wine, but drank a glass of wine? Did other diners eat the same mushrooms, but not had any wine, and escape sickness?

Despite being cooked and chewed, mushroom spores and tissues are still quite recognizable. However, other factors complicate identification. Potato chunks tend to show an amyloid reaction in Russula spores. Some toxins take a long time to become symptomatic in a victim, sometimes up to three weeks, long after leftovers have been consumed.

Thanks to the staff at the Harvard's Farlow Herbarium for their assistance in programming this workshop and the use of the microscopy lab. Also, many thanks to Dave Malloch whose good nature and wealth of experience made for a remarkable workshop!

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