i88 A TEXTBOOK OF THEORETICAL BOTANY 



The hyphae may be either coenocytic or may consist of cells, each possessing 

 one or sometimes two nuclei. In the higher groups the wall of the hyphae 

 is composed of fungus cellulose, which differs from ordinary cellulose in the 

 fact that it does not stain violet with Iodine and sulphuric acid. True cellulose 

 walls occur in certain of the lower groups. 



The reproductive bodies in the lower groups may be small and incon- 

 spicuous, but among the higher members it is the fruiting bodies which are 

 the only obvious part of the fungus, as, for example, in the Mushroom, 

 where the mycelium is underground and passes unnoticed. In almost all 

 groups asexual reproduction by spores occurs, and in many it represents the 

 more general and prolific method of propagation, though in any case the 

 ultimate result of sexual reproduction is also the formation of an abundant 

 crop of spores. In the higher groups the sex organs become more and more 

 reduced until often all that remains as an expression of sex is the union of 

 two nuclei which may be of vegetative origin. 



The Fungi are classified according to the way in which the spores are 

 produced : — 



1. Archimycetes {e.g., Club Root Fungus). 



2. Phycomycetes {e.g., Pin Moulds and Water Moulds). 



3. Ascomycetes {e.g., Morels, Truffles and Blue Moulds). 



4. Basidiomycetes {e.g., Mushrooms, Toadstools and Puff Balls). 



5. Fungi Imperfect! (see under " Plant Pathology " in Volume IV). 



In the Archimycetes and Phycomycetes the spores, and frequently the 

 zoospores, are borne in large numbers in sporangia. In the Ascomycetes 

 the spores are produced in an ascus or sac, each ascus containing usually 

 eight ascospores. In the Basidiomycetes the basidiospores are produced 

 externally in fours on a club-shaped basidium. The Fungi Imperfecti 

 produce only asexual spores. 



ARCHIMYCETES 



The Archimycetes are Fungi devoid of a mycelium, the body of the 

 organism consisting of a naked mass of cytoplasm termed a plasmodium, 

 which finally, after a period of vegetative growth, becomes converted into one 

 or more sporangia. These sporangia may be simple or elaborate structures 

 containing a large number of spores. The spores on germination give rise 

 to motile swarm cells which function as gametes, fuse in pairs and produce 

 a fresh vegetative plasmodium. 



The organisms may be saprophytic or parasitic and are quite common. 

 They probably represent primitive groups of organisms which have not 

 contributed anything to the evolution of the main groups of the Fungi but are 

 rather side lines which have not proved specially successful, but which still 

 exist to the present day as survivals of an early type of fungal organization. 



The limits of this group have been variously held by different authors to 

 include a greater or smaller number of orders of the lower Fungi. Possibly 



