May, 1915. 



KNOWLEDGE. 



133 



and richer growth of the grass in their neighbour- 

 hood. The explanation of the phenomenon is very 

 simple. The fungus plant gets a foothold in the 

 soil in many cases, it is thought, owing to the 

 local manuring of the ground by the droppings of 

 some animal. In due course in the autumn, or in 

 the case of the St. George's Mushroom (Triclioloma 

 gambosum) (see Figure 110) in the spring, a crop 

 of toadstools is produced, and the nourishment of 

 the soil in this area being largely exhausted, the 

 mycelium spreads out in all directions in search of 

 fresh supplies. The result is that next autumn 

 a small ring of toadstools is produced, and, provided 

 that the character of the soil is uniform, every year 

 a larger ring will be found. It is probable that the 

 richer growth and darker colour of the grass are 

 due to the manuring of the soil hy the decayed 

 toadstools of the previous autumn. A friend has 

 told me that he has noticed that a ring of Cham- 

 pignons, or Fairy-ring Toadstools [Marasmius 

 oreades) (see Figure 105) which is growing on his 

 lawn gets a little larger every yea r . When the rings 

 become very large they sometimes cease to extend, 

 and are even said occasionally to get smaller again. 

 Any change in the character of the soil will, of 

 course, tend to break up a ring by producing 

 unequal growth in different regions, and for this 

 reason fairy-rings are but rarely seen excepting 

 where the soil is very uniform ; where the soil 

 changes, or where two rings intersect, they often 

 become broken up. Figure 109 is interesting : 

 it shows a ring of thistles growing just inside a 

 ring of the St. George's Mushroom. I have seen 

 many such rings on the downs, near Lulworth. It 

 may be that there is some symbiotic relationship 

 between the thistle and the fungus by which the 

 growth of the one helps that of the other, or it may 

 be simply that the seeds of each year's crop of 

 thistles are able to germinate more freely in the soil 

 broken up and manured by the toadstools. 



Most wonderful stories are told of the lifting 

 power of growing mushrooms and toadstools. 

 There is an asphalt path in a London garden some 

 part of which is raised every year by a crop of Horse 

 Mushrooms (Psalliota arvensis) (see Figure 103). 

 It is indeed curious that such evanescent and fragile 

 structures as mushrooms and toadstools should 

 be capable of exerting such force. The growth 

 of a mushroom depends on the rapid transference 

 of material from the mushroom plant or mycelium 

 to its growing "fruit." The rapidly growing cells of 

 this attract to themselves large quantities of food 

 matter and fluid which exude into them by osmosis, 

 and by the pressure thus exerted the work is done. 



In cellular structure the fungi differ essentially 

 from most ordinary plants : instead of being 

 formed by polygonal cells pressed together in the 

 form of a mosaic, the tissues of the fungi are com- 

 posed of elongated tubes, divided in some cases 

 by septa, which ramify in different directions, 

 and are_!_more or less easily separated from one 



another. The spaces between these tubes axe 

 filled in with a certain amount of connecting 

 material and by air. Sometimes cross-connections 

 are seen between parallel tubes, so that a figure 

 resembling a capital " H " is formed. When 

 divisions occur in the tubes dividing them into cells, 

 little projections are sometimes seen which connect 

 the two adjoining cells : these are spoken of as 

 clamp-connections. Some fungi also possess much 

 larger branched cells, which contain a milky fluid. 

 The fluid is in some cases clear, but usually white 

 and milk-like, and is sometimes coloured. In 

 Lactariits deliciosus the milk is orange-red. The 

 i-enera Lactariits, Mycsna, and Fislulina all possess 

 this latex, or milky fluid. In some species of 

 Lactarius (see Figure 107) it is acrid and un- 

 pleasant to the taste, and contains a resinous sub- 

 stance. The fluid is probably protective in function, 

 and exudes freely when the fungus is injured. 

 The fact that the cells containing it are most 

 abundant on the surface of the stalk and in the 

 neighbourhood of the gills, regions where any injury 

 would be especiallv harmful, makes this supposition 

 the more probable. 



Fungi have occasionally been observed to give 

 forth a phosphorescent light of a pale yellow or 

 greenish colour. It has been observed especially in 

 connection with Australian species ; and although 

 in some cases it may be due to bacterial action 

 from commencing putrefaction, in most cases it 

 is the fungus itself which gives forth the light. 

 The light is usually most intense where rapid 

 growth is taking place, as, for instance, at the edge 

 of the cap, and has been noticed in the toadstools 

 and mycelia of white spored varieties more than in 

 any other forms. But it has also been seen in rhizo- 

 morphs, and especially in Corticiion cocriilcum, 

 which forms blue films on decaying wood. 



Fungi are very widely distributed in nature, 

 and turn up sometimes in most unexpected places. 

 Even at the rocky summit of the highest moun- 

 tains they are to be found as one of the partners 

 of the joint-stock firms of plants which we call 

 " lichens." M. C. Cooke tells us that about sixty- 

 four per cent, of the larger fungi are terrestrial, 

 about seven per cent, grow on dead leaves, and 

 about twenty-nine per cent, are found on wood ; 

 and, of course, each special locality has its individual 

 fungus flora. Because a fungus is found growing 

 on the ground it is by no means certain that it 

 is obtaining its nourishment from the ground, for 

 it may be attached by visible or invisible threads of 

 mycelium to a dead stump or the root of a tree 

 on which the fungus plant is growing. A few of the 

 habitats of various types oi fungus arc seen in the 

 accompanying photographs (sec Figures 1 1 1 to 1 13). 

 Some varieties arc very exclusive. Claudopus 

 variabilis (sec Figure 114) is generally found 

 growing on dead grass. Collybia conigena (see 

 Figured 15) grows almost exclusively on the cones 

 of firs, and not a few parasitic fungi are confined to 



