MOULDS. 43 



known as fertilization. One cell (the male or sperm cell) is 

 commonly not only smaller, but more active than the other 

 (called the female or germ cell). Example, all higher plants. 



CHAPTER VII. 

 MOULDS ( FUNGI). 



Moulds belong to the class of plants known as Fungi, which 

 latter, as we have already seen, form one of the divisions of the 

 Thallophyta. The fungi are, in their habits, chlorophylless 

 saprophytes or parasites. (A saprophyte is a plant which de- 

 rives its sustenance from decaying organic matter. A parasite 

 lives on other organisms.) In all but a few instances (see 

 Torula), their vegetative parts consist of slender segmented or 

 unsegmented, usually colorless filaments, each one being known 

 as a hypha. These ramify among decaying organic debris or 

 invade the tissues of living organisms, plant or animal, and 

 derive their sustenance from them. In the simpler hyphal 

 forms the hyphse occur singly or more or less interwoven into a 

 tangled felt-work, but they are not gathered into definite forms 

 and have little or no dependence on each other. In the 

 higher groups, however, there is more or less division of labor 

 among the hyphae, and they become consolidated into false tis- 

 sues, which acquire definite shapes according to the species. 

 Of this character are the fructifying organs or carpophores, 

 which constitute the above-ground parts of the agarics, puff- 

 balls, cup-fungi, etc., and the sclerotium, a compact hard mass 

 of thick- walled hyphae, which serves as a resting stage in the 

 development of some species, for example, Ergot of rye. 



Fungi reproduce asexually by means of spores, known as 

 gonidia or conidia. These are, as a rule, thick-walled cells, 

 which become separated from the parent hyphse in ways which 

 are more or less characteristic in the different groups. In all 

 hyphal fungi the hyphae consist of two portions the vegetative, 

 which ramifies in the substratum, often forming tangled, felt- 

 like masses of threads called the mycelium; and the repro- 

 ductive, which comes to the surface. The latter produces the 

 conidia, which may be borne on isolated filaments, as in the 

 bread-mould (Penicillium) or on a carpophore, which produces 

 a spore-bearing hymenium. The common mushroom (Agaricus 

 campestris) is an example of the latter, the plate-like bodies 

 or gills on the under surface of the cap constituting the 

 hymenium. 



In a large number of fungi, including some of the most highly 

 organized forms, sexual reproduction is unknown. In other 



