Jii.v. 1004. 



KNOWLEDGE c<t SCIENTIFIC NEWS. 



MI 



The Inflvience of 

 Fvingi 



For Good on OtKer Forms of Life. 



Geo. Massee, F.L.S. 



In discussing- the various phases included under the 

 subject of the influence of fungi as fa\ouring, either 

 directly or indirectly, the welfare of other forms of life, 

 in the order of their relative importance, the first to 

 claim attention is that of fung-j pla)ing the part of 

 vegetable scavengers. 



When bread, cheese, or other organic substances be- 

 come muddy or mildewed, the general opinion is thai 

 a certain amount of decay has taken place, and therefore 

 mildew appeared as a consequence of such preliminary 

 decay. This idea, however, is not correct, the mould or 

 mildew being the original cause of decay, or change ol 

 composition of the body attacked. The spores of fungi 

 are always present in large quantities in the air, and 

 consequently alight on everything not specially pro- 

 tected. The reason why mouldy food is not universal, 

 seeing that it is so much exposed to the air, is due to the 

 fact that fungus spores can only germinate, and produce 

 a vigorous mycelium, under certain well-defined condi- 

 tions as to temperature, moisture, and the supply ol 

 proper food in an available form. The conditions under 

 which fungi can grow most vigorously varies for every 

 kind. Taking temperature, there is a maximum and 

 minimum of heat, above or below which the spores can- 

 not germinate, hence no growth takes place ; some- 

 where between these two extremes there is an optimum 

 point, at which the spores germinate and form the most 

 vigorous mycelium, provided other conditions are also 

 favourable. 



Cold storage, whether practised in the primitive 

 manner of placing- cooked food in a cool place ; the 

 freezing of raw meat; or the storing of ripe fruit in a 

 cool room for preservation, simply means keeping the 

 substance at a temperature below the minimum point at 

 which the spores of the fungus or bacterium known to 

 attack such substance can germinate. 



No fungus spore can germinate in the absence of 

 moisture. Again there may be too much or too little 

 water for very robust growth, and in the case of 

 heat, there is an optimum or best proportion under 

 which growth proceeds most actively. 



Some few fungi, as the common blue-green mould 

 {PeniciUium glaucum), and the grey mould (Bolrylis 

 ciiierea), show little or no discrimination in the choice of 

 food, and may appear on almost every kind of dead or 

 decomposed plant remains, and also on many animal 

 products. The majority of fungi are, however, very 

 fastidious in the selection of their food, numerous para- 

 sitic species being confined to one particular kind of 

 host-plant ; whereiis some fungi have carried this selec- 

 tive power to such an extreme as to l>e actually limited 

 to one particular variety of a species for their food 

 supply. 



As scavengers the fungi mostly exercise their in- 



lluonco on mcml>crs of the vegetable kingtlom. Leaving 

 for future consideralion the ha\()C. wrought by parasitic 

 lungi on perfectly healthy and vigorous plants, we have 

 slill left a very large number known as suprop/iytcs, a 

 term which includes all fungi tliat obtain their liuxl 

 from dead organic matter. 



When leaves fall in the autumn, or dead br;uiches 

 fall to the ground, or even when whole trees arc blown 

 down, the current opinion is that they decay as a matter 

 of course ; but no one who has not studied the matter 

 can realise the influence exercised by fungi in hastening 

 their decay, and the compar.itivcly rapid conversion of 

 such dead substances into water, ga.ses, and soluble 



I. "Horn of Plenty" {I'vih yilh'S ro)tiucoi.iui'U>^}', Nat. size. 

 An edible funjcus. 



salts, which can again at once bo utilised as food by 

 other plants. 



It is almost impossible to examine any twig or le.af 

 that has been lying for some time on the ground, with- 

 out detecting tlio presence of fungi, either under the 

 lornii of mycelium in the tissues, when, examined under 

 the microsco'pe, or as fruit in the form of .-i toadstool, 

 etc., on the surface. Now these fungi have fed on the 

 twig or leaf — in other words, have converted part of it 

 into a toadstool. 'I"he latter soon perishes in turn and 

 becomes converted into water, saJts, etc., as stated 

 above. This condition of things continues until the leaf 

 or twig becomes thoroughly disintegrated and crumbles 



