SMUT FUNGI— USriLAGINES 257 



The teleutospores in some instances in this family are 

 resting-spores — that is to say, they are capable of germination 

 after a period of rest ; but for the most part they germinate 

 freely when moist, and a delay of germination can only be 

 secured by maintaining a condition of dryness which does not 

 obtain in a state of nature. It is uncertain how the interval 

 is connected between the matm-ity of the teleutospores and the 

 growth of the seedling hosts, where the entire plant is annual. 

 In the case of perennial hosts a persistent mycelium removes 

 all difiiculty, but where mature teleutospores are produced upon 

 an annual in summer or autumn, and there are no seedlings 

 until two or three months afterwards, it is not evident how 

 the continuity of the species is preserved. 



It has been shown that, when cultivated in a suitable 

 medium, the promycelial spores multiply themselves almost 

 indefinitely by budding, but the nutrient fluid must be 

 maintained unexhausted. In this condition the growth is 

 similar to that of yeast, and the term " yeast cells " has been 

 applied to them. So long as the supply of nutrient fluid is 

 maintained there is no departure from the budding process. 

 Brefeld maintains it to be extremely probable that the conidial 

 fructification, in a toruloid form, occurs in nature in many 

 species of the Ustilagineae ; that they have the power of pro- 

 pagating outside the host as " torulae," and develop their spore 

 fructification only when they penetrate the tissues of the host- 

 plant by means of germ threads, which takes place when the 

 supply of nutriment ceases. The extreme assumption on this 

 basis is that certain forms of Saccharomyces, or indistinguish- 

 able therefrom, are in fact aquatic forms of the conidia of 

 Ustilagines, which have become " toruloid " on account of their 

 surrounding conditions. In fact, that some ferments are not 

 autonomous, but depraved Ustilagines which have abandoned 

 their parasitic habit and become saprophytes. 



It will therefore be evident by this time that the members 

 of this family are universally parasitic, and that the hosts are 

 herbaceous plants. In a great number of instances the 

 graminaceous plants are the victims, but by no means ex- 

 clusively. In all cases they are eminently destructive, and, 

 from their habit, difficult to contend with. Most of the pro- 



17 



