386 BOTANY PART n 



The best-known example is Empusa 'inuscae (Fig. 326), which is parasitic on 

 house-flies. The couidia, which are multinucleate, form a white halo around the 

 body of the dead fly which has In-en killed by the fungus. 



3. Basidiobolaceae ('*}.- -Jiasidiobolus ranarum, a saprophytic Fungus growing 

 on the excrement of Frogs, must be separated from the preceding group. Each of 

 the cells of its septate mycelium contains one large nucleus. The conidia which 

 arise singly on the ends of the conidiophores and are abjected when ripe are 

 uninucleate. The mode of origin of the zygospores is peculiar. Two adjoining 

 cells conjugate after they have put out beak-shapcil processes which are cut off as 

 transitory cells. In the zygospore the two sexual nuclei give rise to four, of which 

 two disorganise while the other two fuse. Both in this procedure and in the 

 nuclear structure there are evident resemblances to the Conjugatae (Spirogyra). 



CLASS XIV 

 Eumycetes ( ls 41 ') 



When the Phycomycetes are excluded there remain two great 

 groups of Fungi, the Ascomycetes and the Basidiomycetes, regarding 

 the classification and phylogeny of which' there is still much un- 

 certainty. The attempt has been made to derive them from the 

 Phycomycetes. Not only is the construction of the thallus against 

 this, but the structure of the sexual organs and the development of 

 the fruit in the Ascomycetes indicate on the other hand a remarkable 

 relationship with the Red Algae. The Uredineae or Rusts, one of 

 the simplest orders of Basidiomycetes, appear to connect the latter 

 group with the Ascomycetes. 



The saprophytic or parasitic thallus of the Eumycetes is, like that 

 of the Phycomycetes, composed of fine, richly branched filaments or 

 hyphse which together form the mycelium. The hyphae are, how- 

 ever, in this case septate, consisting of rows of cells. The cell- 

 membrane, which contains chitin, is usually thin. In the colourless 

 protoplasm there are usually numerous minute nuclei (Fig. 62), 

 while in other cases each cell has a pair of nuclei or only a single 

 nucleus. Chromatophores are wanting and true starch is never 

 formed ; the place of the latter is taken by glycogen, often in con- 

 siderable quantity, and by fat-globules. The hyphse of a mycelium are, 

 as a rule, either isolated or only loosely interwoven ; they spread 

 through the substratum in all directions in their search for organic 

 nourishment. In many of the higher Fungi, however, the profusely 

 branching hyphae form compact masses of tissue, AVhere the fila- 

 ments in such cases are in intimate contact and divided into short 

 cells, an apparently parenchymatous tissue or PSEUDO-PARENCHYMA 

 is produced. Such compact masses of hyphal tissue are formed by 

 some species of Fungi when their mycelia, in passing into a vegetative 

 resting stage, become converted into SCLEROTIA, tuberous or strand- 



