FUNGOID DISEASES OF CRUCIFERS 95 



abnormally enlarged and filled with a slimy sub- 

 stance which is the protoplasm of the fungus. 

 After feeding in the 

 cell lor a time, this 

 foreign protoplasm 

 (plasmodium) breaks 

 up and forms numer- 

 ous spores within, and 

 filling up, the enlarged 

 cells (see Fig, 27). 

 These spores are liber- 

 ated in millions in the 

 decaying mass. 



Under favourable 

 conditions the cell wall 

 of the spore ruptures 

 and a small mass of 

 protoplasm is liberated 

 bearing a cilium (hair- 

 like growth) by means 

 of which it is able to 

 move about. Shortly 

 this is resorbed and 

 subsequent movement 

 takes place in a creep- 

 ing manner, i.e. by the 

 small portion of proto- 

 plasm changing its shape. In this stage it is able 

 to enter a cruciferous plant, exactly how and where 



Fig. 26. — Turnip showing the peculiar 

 finger-and-toe-like swellings on the 

 roots caused by Plastnodiophora 

 brassicci ; the upper swellings are 

 in an advanced state of decay. 

 (After Northumberland C.C.) 



