366 APPENDIX 



Enzyme. A complex chemical compound capable of causing the 

 transformation of certain organic substances into substances of 

 greater or less complexity without itself entering into the product. 



Epiphytotic. A plant disease which assumes an unusual and generally 

 destructive nature in a locality. Usually called an epidemic, 

 which term refers only to human diseases. 



Fruiting-body. Large or small, open or closed structures made of 

 mycelium in which the spores of fungi are formed. 



Fungus. Simple plants lacking chlorophyl. Consisting of mycelium 

 which may be massed to form large fruiting-bodies. Fungi 

 obtain food by decomposing living or dead plant and animal tissue. 



Fusiform. SpLudle-shaped. 



Germ-tube. A short tube which grows from a viable spore. The 

 germ-tube then branches and a new mycelium is formed if growth- 

 conditions are suitable. 



Gill. The pendent plates or lamellsB found on the under side of 

 toadstools. The spores of the fungus are borne on the sides of 

 the gills. 



Haustorium (haustoria). Special branch of the mycelium which is 

 pushed into a cell to obtain food-materials. 



Heartwood. The wood at the center of a tree, which contains no 

 living cells and serves only for support. 



Hetercecious. Said of a parasitic fui^fus which requires more than 

 one kind of host for the completion of its life history. 



Host. Any plant in which a parasite grows. 



Hypertrophy. Enlargement of a portion of a plant, as galls on limbs. 



Hypha (hyphse). Individual branches of the mycelium of a fungus. 



Infect. Said of a parasitic organism when it succeeds in establish- 

 ing parasitic relations with a host-plant. 



Infection. The act of infecting, see above. 



Infection court. Any place or area of a host-plant where infection 

 occurs. Also said of any place where infection is possible. 



Lesion. Any definitely diseased area in which the primary cause of 

 the disease is present. 



Mycelium (mycelia). The vegetative body of a fungus, made up of 

 loi^ threads containing protoplasm. 



Parasite. An organism which lives in or on another living organism 

 for the piu-pose of obtaining food-materials. 



Parenchymatous. Tissue composed of thin walled cells which are 

 capable of further differentiation. 



Pathogene. Any factor which causes disease, usually restricted to 

 living organisms which live parasitically. 



Perithecium (peritheeia). A closed globose or flask-shaped fruiting- 

 body containing asci and ascospores. Spores usually forcibly 

 discharged. 



