34 



Gcrminafion of Spores. 



\. In Ustilago nuda the germinal tube does not produce conidia at all, 

 but grows out into a large and copiously branched sterile mycelium. (Fig 4.) 



Fig. 4. Listilcu/o nuda or Naked Barley Smut. — Spore germinating and 

 producing a much-branched mycelium x 350. (After Brefeld.) 



5. In Tilletia tritici the germinal tube produces a tuft of conidia at its 

 apex, and each of these conidia or the conidia united in pairs produce a single 

 secondary conidium capable of infecting the wheat plant. Or the conidia 

 may produce a large and richly-branched mycelium in the air, just like a 

 tuft of mould from which aerial conidia again arise, and this process is repeated 

 as long as the nutrient solution lasts. (Fig. 5.) The important fact is here 

 made evident that the smut fungi can reproduce themselves saprophytically, 

 and that these reproductive bodies are found to be capable of infecting the 

 proper host-plant and of producing the disease. 



fHOnRTY LIBRARY 



M. C. StaU College 



