PLATE B 



I. — Leaf from healthy turnip, control to mosaic turnip in figure 2. 

 2. — Leaf from mosaic turnip, mosaic induced by aphids transferred from mosaic 

 turnip plant. 



3. — Leaf from healthy mustard, control to mosaic mustard in figure 4. 



4. — Leaf from mosaic mustard, mosaic produced by aphids from mosaic mustard. 



(178) 



