THE FUNGI WHICH CAUSE PLANT DISEASE 7 



The decay of the host liberates the spores in the soil. Their 

 germination may be readily studied upon a microscope slide 

 where in from five to twentj'-four hours uninucleate zoospores 

 are produced. The zoospores are differentiated into an inner 





10 11 



TTio 1 _p brassicce: 3, cabbage cells occupied by the unicellular parasite; 5, later 

 stage, parasite many-nucleSte; 10, host cell full of spores; 11, germinating 

 spores. After Lotsy. 



granular part and an outer hyaline part, the hyaloplasm, which 

 may extend to form pseudopodia, thus giving the cell an amoeboid 

 movement in addition to that due to the single long cilium. In- 

 fection by these swarm spores is supposed to occur through the 

 root hairs though the mode of primary infection is not definitely 



