the species and, although produced in enormous numbers, are 

 always very minute. In the larger fungi they are borne on 

 an elaborate cap-shaped structure, e.g., the cap or edible portion 

 of a mushroom. Anyone can demonstrate the vast quantity 

 of spores which are produced by a mushroom by cutting off 

 the stalk and laying the cap, gills downward, for a few hours 

 on a plate or piece of white paper and covering with a tumbler. 

 A copious fall of spores will be found and an outline of the gills 

 will be seen on the paper. If the cap is not covered only a few 

 spores will be deposited owing to their being blown away as 

 they fall by draughts. 



Precisely the same spore-discharge takes place daily in 

 orchards and gardens. Silently and unobserved, fungi both 

 large and small, are, if the weather be favourable, discharging 

 myriads of dust-like spores. Most of these are wafted as a 

 totally invisible dust over neighbouring plants or neighbouring 

 fields; some may be blown away in bulk, others washed down 

 by rain. The big toadstool may discharge its hundred millions, 

 the Coral Spot fungus its one million, but in all fungi, when 

 the reproductive phase is reached, an exceedingly copious crop 

 of spores is developed. 



When it is remembered that this spore-discharge takes place 

 all over the country and that, borne by the breeze, spores are 

 rained on every garden, field and orchard, the sudden appear- 

 ance and rapid spread of a mildew like American Gooseberry 

 Mildew or a tree disease like Silver Leaf is no longer myste- 

 rious. The wonder is that fungus epidemics are not more 

 prevalent and that, relatively speaking, so very few spores 

 fulfil the function for which they were produced. 



Saprophytes and Parasites. As is the case with seeds, spores 

 germinate under suitable conditions of warmth and moisture. 

 Each spore gives rise to fresh mycelium and thus produces a 

 new plant. Whether this infant fungus will grow and mature 

 depends on the nature of the substratum Fungi differ 

 enormously in their requirements. Some are so adaptable that 

 they can flourish almost anywhere where moisture and- vege- 

 table matter of any kind are present. Others have a more 

 restricted range, requiring either leaf mould, dead wood or 

 rotten fruit as the case may be. Yet others show a decided 

 tendency to feed on living organisms and thus pass from the 

 realm of harmless saprophytes (i.e., organisms that live on 

 dead organic matter) to that of parasites. 



Types of Parasitic Species. As far as the present volume is 

 concerned, the interest lies wholly with the parasitic species. 

 These show varying degrees of parasitism and, for this and 

 other reasons, there is considerable diversity in the amount of 

 damage they cause. There are the feebly parasitic fungi which 

 occur abundantly on dead shoots, but under certain conditions 

 spread into the living tree and cause damage. Amongst species 

 of this class attacking fruit trees Coral Spot is a good example. 

 Others, although they commence on a dead branch or wounded 



