GENERAL ACCOUNT OF FUNGI. 425 



with protoplasm, and in certain cases may remain alive up 

 to 3 or 4 years. Conidia and carpospores germinate when 

 they meet with favourable conditions of temperature and 

 moisture ; it may be laid down as a general rule, that conidia 

 serve to reproduce the fungi in great numbers, while the 

 carpospores carry on the species over winters or prolonged 

 dry seasons. 



Fungi do not usually require the same amount of heat as 

 the higher plants for their development, and their fructifying 

 organs are usually most numerous in October. As already 

 stated, they may be either saprophytic or parasitic, while 

 some fungi are epiphytic, living on the epidermis of leaves or 

 shoots, and merely piercing into it from time to time with 

 delicate minute haustoria, or root-like ramifications of the 

 hyphae, which are devoid of any root-cap. The mycelia of 

 parasitic fungi live on or in the tissues of living plants or 

 animals, tiieir spores gaining admission into the former through 

 wounds, lenticels or bark-cracks, or through the stomata of 

 leaves or young shoots, or the soft growing points of roots. 

 There they germinate, and emit tender thin- walled, generally 

 colourless hyphae, which, when very young, are filled with 

 protoplasm ; but cell-sap or bubbles of air soon occupy part 

 of their lumina, the protoplasm then merely lining the walls 

 of the. hyphae or passing into younger cells. Oil may also 

 be found in the hyphae, especially when they pass through 

 tissues of the host which are rich in reserve-material. This 

 oil is frequently of a golden-yellow colour, as in many kinds of 

 rusts on leaves or shoots. 



The hyphae grow by their apices, and their terminal cells 

 are always rich in protoplasm. In the case of parasitic fungi, 

 the hyphae may grow either in an intercellular manner between 

 the tissue elements or in the resin-ducts and other intercelkilar 

 spaces, merely sending their haustoria into the lumina of the 

 tissue-elements, or, if the hyphae are furnished at their apices 

 with a ferment capable of decomposing the cell-walls, they 

 themselves penetrate through the cell-walls of their host, and 

 thus pass from one cell to another. As they proceed, the 

 younger cells of the hyphae procure protoplasm from the older 

 cells, in which eventually nothing but air is left. 



