Junk, 1915. 



KNOWLEDGE. 



167 



many fungi is their brilliant colour. About the 

 chemistry of this but little is really known ; 

 but we are told that in many cases the colour is 

 due to chromogenous materials, which on oxidation 

 develop the characteristic tints. We know how 

 rapidly the colour of some species of Boletus 

 changes when the flesh is broken and exposed to 

 the air. But it is probable that presence of light 

 has something to do with the production of colour 

 also, at any rate, in some species; for Fischer found 

 that in experimental cultivation the fruits of 

 Armillaria mucida, grown in the dark, were always 

 white, while those grown in the light were grey or 

 brown. Decaying branches of oak may often be 

 picked up in woods, stained all through a brilliant 

 verdigris-green colour. On the surface the wood is 

 soft and easily broken, but further in, though it 

 retains its brilliant colour, it is nearly as hard as 

 ordinary wood. In the days before aniline dyes 

 these half-decayed logs were used for the beautiful 

 inlaid woodwork known as " Tonbridge ware." 

 In autumn tiny green cups may often be seen 

 growing on the fallen branches. They are the fruits 

 of the fungus Peziza (Hclotiuvi) aeruginosa (see 

 Figure 147), the mycelium of which is responsible 

 for the bright green colour. The oak wood is 

 penetrated in all directions by the fungus hyphae, 

 and these contain the bright green substance 

 which can be separated as a chemically pure 

 crystalline material, and is thought to serve as 

 a reserve store of nourishment for the fungus 

 plant. 



It is very difficult to understand of what \-alue 

 these brightly coloured substances can be to the 

 fungi which possess them. Although a few fungi 

 are regularly eaten in nature by animals and insects, 

 most of them, including some of the most brightly 

 coloured species, are practically never touched by 

 any creatures that could possibly assist them in 

 the distribution of their spores. Moreover, the 

 umbrella-like form — which has proved so successful 

 in the struggle for existence that it is found in 

 many thousands of different species of toadstools — 

 is so excellently adapted for the distribution of 

 the light spores by the wind that it is difficult 

 to imagine that it has been evolved for any other 

 purpose. The brilliant tints of many of these 

 toadstools would seem to be due to no mere accident, 

 and to be something more than a method of disposal 

 of material of no further value to the plant, as 

 they are in most cases limited to that part of the 

 toadstool visible from above, and are even confined 

 in very many cases to a thin layer of tissue on the 

 upper surface of the toadstool cap. Possibly the 

 bright colours have been evolved for the purpose of 

 making the toadstools conspicuous, so that they 

 may be avoided, and neither trodden on nor eaten 

 by accident or mistake by grazing animals. 



In conclusion it may be interesting to enquire 

 of what economic importance is the toadstool tribe ; 

 and it must be admitted at once that, from the 



point of view of civiHsed man, the fungi are of little 

 use, and do an infinite amount of damage. Many 

 of the most serious of the diseases of cultivated 

 plants are due to microscopic fungi ; and, as has 

 been already described, much disease in timber is 

 the result of the growth of parasitic toadstools — 

 indeed, it has been stated that the world is poorer 

 by no less than two thousand million pounds sterling 

 every year owing to the loss of crops which have 

 been attacked by fungus pests. Turning now to 

 the other side of the picture, it is well known that 

 mushrooms and toadstools are much more exten- 

 sively eaten abroad than in England. But from 

 what has already been said it will be inferred that 

 the edible fungi must be regarded as a pleasant 

 (though often dangerous) flavouring agent, rather 

 than as a sustaining food. In the olden times 

 several of the fungi were used medicinally. The 

 familiar Jew's-ear (Hirneola auricula-judae) (see 

 Figure 1 50) had a great reputation for the treatment 

 of dropsy, and every \\ise house-wife kept a store of 

 dried giant puffballs (Lycoperdon giganleum). 

 to be applied to cuts to stop bleeding. At the 

 present time Ergot is the only fungus regularly 

 used in medicine ; but this drug and the preparations 

 made from it are of very real value in the treat- 

 ment of disease, nor have we any other drug with 

 similar physiological properties which can replace 

 it. Some of the larger woody forms, such as Fomes 

 foment.irius, when dried and beaten, form a soft, 

 velvety material. Hats and slippers, blotting 

 cases, and so on, are made from this in South-eastern 

 Europe ; and, being very absorbent, the same 

 material, under the name of "Amadou," is used 

 by dentists for mopping out the ca\'ities of diseased 

 teeth which are being stopped. Razor-strops can 

 also be made from the woody fungi. I have a 

 useful strop made from a piece of a large fruit 

 body of the Birch Polyporus [Polyporus bctulinus) 

 (see Figure 134), which answers its purpose very 

 well. Dried fungi have been used for tinder, 

 and the fumes from smouldering giant puffballs 

 served in olden times to stupefy bees before they 

 were robbed of their honey. 



