FUNGI 13 



spores remain firmly attached to the leaves, and may 

 often be found in a living condition on rotten straw in 

 a manure-heap. 



During the spring following their production, the 

 teleutospores germinate, giving origin to a few very minute 

 reproductive bodies called secondary-spores (Fig. 2, 7), 

 which are dispersed by wind. Such of these as alight on 

 barberry leaves give origin in turn to the aecidium or 

 cluster-cup stage of the fungus. 



The above account briefly describes the complete life- 

 cycle of wheat rust ; but it is important to remember that 

 the continuance of the species does not require that it 

 should be repeated every season. The uredo or summer- 

 spore condition alone is sufficient to perpetuate the disease 

 from year to year, growing during the winter on the leaves 

 of wild grasses in sheltered situations, as hedge-banks, etc., 

 and passing from thence to young wheat. 



In addition to the above, and other modes of repro- 

 duction by means of various kinds of conidia or spores, 

 fungi are also reproduced by the mycelium or vegetative 

 portion of the fungus, which under certain conditions 

 becomes highly specialised for this purpose. The most 

 usual form of vegetative reproduction consists of densely 

 compacted masses of hyphae called Sclcrotia. These 

 sclerotia are globose or irregularly shaped masses, varying 

 in size from that of a pin's-head to a cricket-ball, depending 

 on the fungus to which they belong. The outside is 

 generally blackish, the inside white. These bodies are 

 formed, often in large numbers, in the substance of the 

 plant on which the fungus is growing. When the host- 

 plant decays, the sclerotia remain in the soil in an 

 unchanged condition until the following season, when 



