48 MYCOI,OGY 



its extremity, as it grows beneath the bark, or penetrates the soil (Fig 

 15). Such a compound thallus differs strikingly from the filamentou 

 thalluses of the two previously described fungi. The union of th 

 hyphal cells in some of these fleshy fungi may be so intimate as to con 

 stitute a pseudoparenchyma, and this close union of the cells may b 

 made still more intimate by clamp connections where two adjoining cell 

 are bound together endwise by a clamp-like protuberance of one of th 

 cells attached to the end of the other adjoining cell. When the pseudr 

 parenchyma is external, it may serve for the protection of the internal! 

 disposed hyphae, and be looked upon as protective tissue. Mechani 

 tissues for the support of fungi are not unknown in some of the g^oup^ 

 as in some of the polypori; where there are clamp connections, tran^ 

 verse septa and thickened cell walls. A few of the higher fleshy fun{. 

 have conducting hyphae, which are larger and more tubular than th 

 surrounding hyphas, and which conduct later, oil and other substance^ 

 Those which conduct a milky juice, as in some species of Russula an 

 Ladarius, may be termed laticiferous hyphae. There are some fungi i 

 which the hyphal form of thallus is not present. The yeasts are eithc 

 single ellipsoidal cells, or these cells are loosely connected together i 

 a chain of bed-like cells. These chains are due to the budding < 

 sprouting method of cell multiplication where a bud, gemma, or sprou 

 grows out from the mother cell as a daughter cell. It in turn buc 

 producing a granddaughter cell and so forth. Such a method < 

 reproduction is known as gemmation. 



In the parasitic fungi, the hyphae run either into the cells, throng 

 the cells (intracellular), or between the cells (intercellular). Whei 

 the hyphae are intercellular, short branches may be formed whic 

 penetrate the host cells. These short branches take various forms an 

 are known as kaustoria; a single one as an haustorium (Figs. 36 and 67 

 Occasionally in the mildews, the mycelium may be superficial an 

 hence epiphytic, while the mycelia which are internal are endophyti 

 These are useful terms when describing the parasitic habits of fung 

 Some of the groups of fungi have mycelia that form resting bodi( 

 of hyphae. These are the most compact of all forms of mycelia an 

 are known as sclerotes (sderotium — ia), which in many cases assun 

 tuberous forms. They are resting states of the mycelia and act ; 

 stores of reserve material. These are some of the principal forms . 

 the vegetative thallus of the fungi. Further details will be given i 

 he discussion which follows. Some sudden epidemics of rust funj. 



