94 FUNGI. 



becomes the germ-tube. The protoplasm accumulated in the 

 spore enters the hypha, which, in pure water, can only grow as 

 long as the reserve nourishment lasts. 



2. GERMINATION WITH PROMYCELIUM differs only by the circum- 

 stance that the hypha developed from the germ-tube has a Tery 

 limited growth, and hence it does not immediately develope into a 

 mycelium, but produces conidia (Rust- and Brand-Fungi). This 

 promycelium must only be regarded as an advanced development 

 of a conidiophore or basidium. 



3. THE YEAST-FORMATION of conidia consists in the production 

 of outgrowths, very much constricted at their bases, from one or 

 more places. Each of the conidia formed in this manner may 

 again germinate in the same way. When sufficient nourishment is 

 present, a branched chain of such conidia is formed, and these are 

 iiiially detached from one another. Yeast-like buddings from the 

 conidia are produced in various Fungi, e.g. Ascoidea, Protomyces, 

 Ustilaginece, Ascomycetes, Tremellacese, etc. In the Ustilaginese 

 these conidia are an important element in the development. 

 The budding conidia of Exobasidium forms a " mould " on the 

 nutritive solution. The yeast-like conidia are not to be con- 

 founded with the " Mucor-yeast " (comp. Mucoraceae). For Sac- 

 charomijces see Appendix to the Fungi, page 176. 



In a compound spore (i.e. when a mass of spores are associated 

 together) each spore germinates on its own account. There are 

 sometimes, however, certain among them which do not germinate, 

 but yield their contents to those which do. 



The length of time for which conidia can retain their power of 

 germination is shortest (being only a few weeks) in those having 

 thin walls and containing a large supply of water (Peronosporaceae, 

 Uredinaceae). In many spores a resting period is absolutely neces- 

 sary before they are able to germinate (resting spores). It has 

 been observed in some spores and conidia, that the faculty of 

 germinating may be preserved for several years if the conditions 

 necessary for germination remain absent (Ustilagineae, Eurotium, 

 Penicillium). 



The optimum, minimum and maximum temperatures required 

 for the germination of the spores has been decided in the case of 

 a good many Fungi. A large portion of the most common Fungi 

 have their optimum at 20C., minimum at 1-2C, maximum at 

 40C. In the case of pathogenic Fungi the optimum is adapted to 

 the temperature of the blood. Fungi living in manure, whoso 



