22 Gcrnii nation of Spores. 



other liquid medium, others ou the surface of it, and still others require only 

 damp air, for if they come in contact with water they are abnormally 

 developed. The time required for germination is also very variable, as it 

 may occur within a few hours or take several days, as in the case of Tilletia 

 tritici. No doubt this is dependent on various factors, such as the age of 

 the spore and the conditions of the weather, which is most favorable when it 

 is warm, damp, and cloudy. 



Duration of Germixating Power. 



In quite a number of casei the spores are capable of germination as soon 

 as they are mature, and where cereal crops are concerned, this immediate 

 germination w ould evidently tend to the extinction of the fungus, since there 

 would be no suitable host-plant to infect at that season, and so the conidia 

 formed would probably perish. But it is now known that under such 

 circumstances special conidia are formed, which have the property of living 

 on dead or decaying vegetable matter, and thus tiding the fungus over the 

 period when living plants are not available. In the case of Loose Smut of 

 Oats, for instance, Brefeld brought about infection by means of the sprouting 

 conidia derived from the budding conidia grown in a nutritive solution. 

 In other cases the spores are only capable of germination after a period of 

 rest, and so are ready to infect the host-plant at the next period of vegetation. 

 This period of rest may extend over a number of years, if the conditions are 

 not favorable for germination. Thus the bunt spores have been known to 

 retain their vitality for eight years and a half when kept perfectly dry, and 

 the spores of Tolyposporium bursiim on kangaroo grass have germinated after 

 four years, the spores having been collected in November, 1902, and germinated 

 towards the end of 1906. 



Types op Germination. 



It was formerly taken for granted that .smut fungi could only live and 

 grow upon the host-plants with which they were found associated in nature, 

 and experiments and observations were accordingly confined to these hosts. 

 It was known that the spores could germinate in water just as they would 

 on the moist surface of the plant, but beyond that there was no independent 

 existence supposed to be possible. When it was discovered, how^ever, that 

 these smut spores could live and grow outside of the host-plant, then it was 

 realized that their developmental history could be followed apart from the 

 living organism. It is to Brefeld we owe this new point of view, which has 

 been so fruitful in results, and the use of artificial nutrient solutions, instead 

 of mere water, was the starting-point. 



By studying the germination of spores in this way we have learned that 

 there are various types of germination, and concrete examples, occurring in 

 AustraUa, will be given of each type. 



1. In Vstilago avence the germinating spore produces a germinal tube 

 bearing conidia, and these conidia multiply rapidly m the liquid by sprouting 

 in a yeast-Uke manner at both ends. (Fig. 1.)* Each of these daughter 

 conidia is capable either of repeating the sprouting in a nutritive solution or 

 of directly infecting the young seedling. 



* Text figures are simply referred to as Figures, while tliose beloiuing to the Plates are always 

 preceded by the number of Plate. 



