FUNGOID DISEASES OF PLANTS 133 



development of the same parasite, which having completed 

 its circle returns to the first once more. For instance, the 

 little red spots called "cluster-cups" on bramble or 

 barberry was once classed as jEcidium herberidis, and 

 the orange-coloured ovals found on grasses and corn 

 was called Uredo segetum. They are now known to be 

 one and the same plant, Pwccmm graminis, or Wheat 

 IVIildew. In the full-gro\vTi fungus there is often little 

 to distinguish between root, stem and flower, judging 

 by ordinary standards, at least in the tiny organisms 

 we are here dealing with. The cells are all much of a 

 muchness, being a collection of thin-walled boxes of 

 protoplasm, the gelatinous substance which is the basis 

 of all life. 



Some examples are shown on Plate 30 of familiar moulds 

 and mildews, which illustrate the simplicity and yet the 

 endless variety of fungal growth. 



It will be noticed that in all these examples the main 

 object of the plant appears to be the production of the 

 little round bodies marked *' s," which are the spores, 

 and this is in fact the case. 



These tiny, invisible spores, once released from the 

 parent plant, from which they are often expelled with a 

 sudden jerk, float about in the atmosphere and are wafted 

 on to decaying matter, or on to the soil or the host plant 

 as the case may be, until conditions favour their develop- 

 ment into full-grown fungi to carry on the same process 

 once more in their turn. This explains the otherwise 

 unaccountable appearance of a fungus disease where 

 least expected. The offending spores may have rested 

 dormant for an indefinite period, or have been blown 

 along by chance in the breeze. 



It is always at the spore stage that we must seek to 

 break the chain and check these troubles, as the harm 

 is done once they germinate. How is this to be accom- 

 plished ? 



Now if there is one thing above all others that fungi 



