46 MYCOLOGY 



branches are coarser in Penicillium and do not form the fine-pointed 

 ends found in Mucor. The presence of transverse walls in the fungi is 

 thought of sufficient importance to make a subclass known as the 

 MYCOMYCETES to contain all of the true fungi EUMYCETES 

 which have a mycelium which is multicellular in contradistinction 

 to those which have unicellular mycelia and that form the subclass 

 PHYCOMYCETES. From this spreading myceHum of transversely 

 septated hyphae in Penicillium arise hyphae which branch at the 

 extremity into a number of erect branches from the ends of which 

 are cut off in sequence a series of small round cells, the spores, which if 

 undisturbed remain connected in a chain, so that the 

 fructification roughly resembles a small broom, or 

 whisk. The large vertical hypha is a conidiophore, 

 and as the spores are pinched, or abstricted off from 

 the secondary branches as single cells, they are 

 known as conidiospores {kovls, dust + airopa a seed) 

 (Fig. 14 and Figs. 243 to 263 inclusive). 



The third example, which we will use to describe 

 in general terms the vegetative organs of the fungi, 

 is the honey-colored toadstool, Armillaria mellea 

 (Fig. 15). The toadstools, or fruit bodies, often form 

 Fig. 14. — Con- dense clumps around the base of some dead or dving 

 mo°n ""Te'en-mouS; tree, or almost cover an old stump on which ihey 

 Penicillium glau- grow. The Cap is of a houcy-colored brown, about 

 llZnr'^oi ^coSSo- two inches across, and the stem may be six inches 

 spores. (After Conn, long and paler than the cap. Microscopic sections 



that are closely bound together to form the stem and 

 cap. If we examine the base of the stalk, we find that it arises from 

 a dark-colored cord-like strand which has been termed a rhizomorph 

 because of its resemblance to a root (Fig. 15, II and IV). These 

 rhizomorphs constitute the mycelium and they either ramify through 

 the soil, or else are found beneath the bark of the dead tree, where 

 they unite to form open-meshed nets of a dark brown color. These 

 rhizomorphs are strands of hyphae that run longitudinally. The 

 hyphal cells are bound together in a cord-like cable which is peculiar 

 in that it shows apical growth, constantly elongating at its extremity, 

 as it grows beneath the bark, or penetrates the soil (Fig. 15) 



