The Treatment of Fungi. 229 



flowering plants, it possesses no chlorophyll. Chlorophyll is the 

 green-colored protoplasm found in flowering plants, and it is the 

 only substance we know through which plants change crude food 

 to nutritive material. We must conclude, therefore, that fungi 

 do not prepare their own food, but feed upon organic matter 

 which is already adapted to their wants. They possess no 

 leaves, flowers, nor seeds. That part of any fungus which is 

 of most interest to the horticulturist is composed of long, fine 

 threads, either grow ing separately or in bundles ; these threads 

 are known as hyphae, and collectively they form the mycelium 

 or vegetative portion of the fungus. The mycelium corresponds 

 to the roots and stems of flowering plants. 



Spores, which are organs performing the same office as the 

 seeds of flowering plants, are produced by this mycelium either 

 directly, or upon branches (sometimes called sporophores) which 

 are thrown out. These sporophores cause the white downy 

 appearance seen upon grape leaves affected with the downy 

 mildew. A spore, strictly speaking, is not a seed, for a seed 

 contains a young plant, while a spore does not, being usually 

 composed of only one cell. If a spore finds the proper condi- 

 tions of heat and moisture it will germinate and send out a 

 fine filament, which, if nourished, grows and branches, and 

 eventually a plant like the original will be produced. 



Most fungi in the North produce two kinds of spores, known 

 as the summer and the winter spores. The summer spores are 

 usually borne upon the exterior of the host-plant, or the plant 

 on which the fungus grows. These spores ripen quickly and 

 propagate the fungus rapidly. But if they do not germinate 

 soon after ripening they lose their vitality. 



The winter spores are usually produced within the tissues of 

 the host-plant, commonly in the leaves and fruit. They are 

 the spores which live through the winter; but in the spring, 

 under favorable circumstances, they germinate, and thus the 

 fungus is again developed. 



Fungi may be divided into two general classes : those grow- 

 ing upon dead and decaying matter, or saprophytes ; those feed- 

 ing upon living tissue, or parasites. By far the larger portion 

 possessing interest to the horticulturist belong to the latter 

 class, for in this are included the fungi which do so much 

 injury to cultivated plants. 



