MYXOMYCETKS. SI. IMF. MOLDS 



99 



varieties of cabbage, cauliflower and Brussels sprouts (I>njssicd 

 olcraccii}, turnip (Umssicii i'iijnj>cstris), rutabaga (Hnissifa AW/w), 

 radishes (Rap/ianns siiti-ra), and certain mustards (Sinapis and 

 Brassica). It has also been found upon such weeds as shepherd's 

 purse (Cafscllii Unrsa-fastoris) and hedge mustard (Sisywbrhnn 

 officinalc). In Europe besides most of the plants mentioned Mathi- 



Fi<;. 20. ACROSS SKCTIO.N OK CABBAGE I\<>>i AFFECTED I;Y mi: 

 ROOT Fr.xGus. (Invaded cells enlarged and phloem tissue multiplied) 



ola incana and Iberis umbcllata are hosts. There seems to be little 

 recent data of interest bearing upon the comparative susceptibility 

 of different varieties of cultivated plants. Many mistakes have 

 doubtless been made in assigning to this fungus injuries appear- 

 ing upon other orders of host plants, and sometimes even those 

 upon crucifers, due to nematode worms. It is often difficult to 

 distinguish between the two causes of disease. 



