GENERAL INTRODUCTION 11 



addition to the proper f I supply for their growth, moisture and 



temperature are the two most important factors for the rapid 

 development of the fungi. The fruit-bodies of mushrooms contain 

 ;i very high proportion of water, varying between 7" and 95 per cenl 

 according to species, weather conditions, age of plant, etc. The 

 mycelium is also composed of much water which fills the vacuoles 

 no1 occupied by the protoplasm. In spite of this fact, a far greater 

 number <»r species occur in the upland foresl than in wel Bwamps 

 or marshes. Ii appears as if either some unfavorable soil contenl of 

 a poisonous nature or too great an abundance of water prevents the 

 mycelium of many species from growing in low wet places or al 

 leasi prevents them from fruiting. Only certain kinds grow in marsh 

 soil; although where there is an abundance of brush, Logs or debris 

 which ran be used for support the moist surroundings are very 

 favorable to forms which prefer such substrata. The Largest num- 

 ber of species are found in forest hillsides, ravines, etc., where there 

 is a clay subsoil or where the forest floor is covered with sufficient 



humus, dead leaves, thick moss or other debris to hold the moisture. 

 With the moisture content neither too large nor too small in such 

 situations and where severe drying out is prevented, it would appear 

 that the mycelium can vegetate luxuriantly, and alter rains, es- 

 pecially Long continued rains, the fruit-bodies or "mushrooms" 

 form abundantly. 



The temperature must also be favorable for each species. Warm 

 or "muggy" weather, continued for several weeks with accompany- 

 ing rains, usually causes the woods and fields to bring forth a g I 



crop of mushrooms during July and August. Later, in September 



and October, an entirely different group of species appears, often 

 in relatively cool weather; and some species often appear after the 

 first frosts, always provided that the soil has been previously 

 moist enough for the mycelium to vegetate sufficiently. Romell 

 (Hymen of Lapland), reports that Agarics were abundant near the 

 tree line, and even in the region along the tree limit right up to the 



li f perpetual snow. This would indicate that for some species 



temperature is not so important as moisture, although growers of 

 mushrooms in artificial beds in cellars, etc.. find the temperature a 

 very critical factor. 



It must be remembered that time i> also an element. After a 

 drought it may take several weeks of steady rains before the fruit 



bodies appear above ground. Rotten wood and Logs retain the 

 moisture and a single rain is ..lien sufficient to induce growth. \ 

 Single heavy rain or even a number of scattered showers, if [mo far 



