122 



FUNGOUS DISEASES. 



are a sure sign of the black rot, showing that the 

 germs have already passed from the leaves into the 

 stems. 



If the stem of a healthy cabbage leaf be cut 

 across, these vessels are seen forming faint yellowish 

 spots in the interior, in marked contrast to the black 

 spots seen in the badly diseased leaf. In case of 



Fig. 26 Healthy Cabbage Leaf, Showing Water Beads Along 

 the Margin. 



leaves which are but partly diseased, only those ves- 

 sels leading into the diseased areas will become 

 blackened. Anyone seeing suspicious looking leaves 

 on his cabbage plants may therefore readily satisfy 

 himself as to whether it is this black rot, by cutting 

 off the dying leaf stems and examining their freshly 

 cut surface for these black dots. If it proves to be 



