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very minute and with a structure scarcely more elaborate 

 than that of the bacteria. The common Brewers'- 

 Yeast Plant, for instance, consists of single, oval 

 cells, each cell having a diameter of about ~^ of an inch. 

 It can, however, be at once distinguished from the bacteria 

 by, among other things, its considerably larger size, its 

 peculiar mode of multiplication by what is known as budding, 

 or sprouting., and ' by the way in which the spores are formed 

 as will be clear from the life-history given below. The 

 majority of fungi, however, have a much more elaborate 

 structure than that of the simple Yeast Plant, and, although 

 they never show traces of leaves, there is commonly a more 

 or less clear differentiation into root-like and shoot-like portions. 

 Special spore-bearing organs are commonly developed and 

 sexual reproduction is often met with. Many of the simpler 

 forms resemble colourless alga3. Some fungi then are unicellular, 

 but the majority consist of slender, thin- walled, more or less 

 branched filaments, or tubes, called hyphae, which are only 

 capable of growing in length at their apices. These hyphae 

 may possess cross- walls which thus divide them into segments, 

 in which case they are said to be septate, or they may be 

 aseptate, i.e. undivided. The whole vegetative body of the 

 fungus consists of these hyphae and is called the mycelium. 

 This ramifies in the substance from which the fungus derives 

 its nourishment and absorbs the necessary food materials 

 from it and, like the roots of higher plants, usually remains 

 out of sight. Fungi are, therefore, best known by their 

 reproductive organs, which are developed at the surface of the 

 substance on which the fungus is growing, or on aerial bran- 

 ches of the hyphae. Sometimes the mycelium is superfi- 

 cial and only specially developed short branches of the hyphae, 

 termed haustoria, or suckers, penetrate the substance on which 

 the fungus is growing and absorb the necessary food 

 materials. 



The mycelium may consist of a few delicate hyphae and 

 thus be invisible to the naked eye, or the hyphae may be 

 collected into dense masses and become visible in the form 

 of papery or skin-like membranes, or thick, felt-like sheets 

 and masses. In some species the slender thin-walled hyphae 

 are united into bundles, which are provided with a hard, 

 dark-coloured, protective coat. Such strands may some- 

 times be mistaken for the fine roots of higher plants, which 

 they resemble in general appearance, and they are, in conse- 

 quence, termed rhizomorphs. or root-like structures. Pro- 



