- or is someone in the BBC taking the mickey?
Last week, on a David Attenborough programme, he said that cistus leaves could spontaneously combust if they reached 32ºC. A sequence showing a blazing plant accompanied his commentary, but the leaves looked nothing like cistus.
This seemed a bit odd, as we have lots of cistus in the garden, and I've never seen one burst into flames, so I googled "cistus spontaneous combustion" and came up with http://www2b.abc.net.au/tmb/Client/Message.aspx?b=72&m=19846&dm=1&pd=2&am=20337 , where someone says they contacted Attenborough and Kew Gardens, but did not get a satisfactory explanation.
There is mention elsewhere of sponataneously combustion occurring in some resinous plants, but at 400 to 600ºC, not 32ºC!
Then, yesterday, in an Attenborough epic about migrating salmon, he stated that salmon could identify one molecule of water from their home river in something like a million litres - or was it more than that?
Please! A molecule of water can have distinct properties? What next? Someone really must be putting stuff in the script for a laugh, and somehow he's reading it.
It does seem that salmon are believed to find their way to their home river by olfactory memory, but that involves recognising odour molecules in the environment, not water molecules from a particular river.
I don't know how good salmon are, but a shark is reputed to have a very highly developed sense of smell, and can detect blood in a concentration of about 1ppm, equivalent to 1 drop of blood in about 50 litres of water. That is roughly one molecule of blood in about 1/36,800,000,000,000 of a cc. Quite a lot less than a million litres!
I just don't believe salmon are 37 billion times better at smelling than are sharks.
Note: A drop of water contains about 1.84 x 10^21 molecules, a litre is about 20,000 drops.
I stopped believing the BBC long ago.
But now I can't even believe David Attenborough !
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