10 Karl Hermann Fernow 



large yellowish green areas intermingled with large patches of dark green. 

 Sometimes the lighter areas predominate, but usually the darker part is 

 more extensive. Sometimes the darker areas appear as blisters. Not 

 infrequently, if the plant is affected early, the leaves may be considerably 

 distorted. The flowers also have been observed to be distorted and 

 abnormally pigmented, as described by Allard (1914). 



Mosaic G on Phaseolus vulgaris (Plate V, 21) is generally manifested 

 by a mottling consisting of rather large, well-defined patches of light and 

 dark green. The younger leaves are often reduced in size, and cupped. 



Mosaic A on Physalis heterophylla Nees is similar in appearance to the 

 ordinary tobacco mosaic. 



Mosaic A on Physalis subglabrata Mackenzie & Bush (Plate II, 12) 

 is also similar in appearance to tobacco mosaic. 



Mosaic E on Phytolacca decandra is similar in appearance to tobacco 

 mosaic, but the leaves are seldom blistered. The mottled areas are gen- 

 erally large. 



Mosaic F on Rumex obtusifolius shows as a rather fine, regular mottling, 

 not very striking. 



On Solanum aculeatissimum Jacq. (Plate V, 22) both mosaic A and 

 mosaic B occur. Neither ordinarily produces striking symptoms, and 

 the writer has thus far been unable to distinguish between them with any 

 degree of certainty. It would appear that the contrasted areas were 

 generally larger for mosaic A than for mosaic B. 



Solanum atropurpureum Schrank and S. carolinense appear to be subject 

 to both mosaic A and mosaic B. As in the case of >S. acideatissimum, 

 the two mosaics are not readily distinguished, but mosaic A seems to pro- 

 duce larger contrasted areas than does mosaic B. 



Solanum nigrum L. has reacted positively to mosaic A only, in the few 

 experiments performed. The mosaic produced is rather striking, and 

 resembles mosaic A on tobacco. 



Solanum tuberosum L. has been found to be subject to both mosaic 

 A and mosaic B. Inoculations with mosaic A by grafting produce very 

 remarkable symptoms. The young shoots of the potato are affected with 

 what was at first thought to be an attack of early blight. Small yellow- 

 ish spots show on the leaves. These spots soon die and turn brown. The 

 petioles and the young stems become affected with a severe necrotic 

 streaking and the affected shoots generally die soon after. Sometimes no 

 symptoms appear until the second vegetative generation. The second- 

 generation plants are usually much dwarfed (Plate VII, 25) and the leaves 

 may show from one to five yellowish spots which soon become brown. 

 As these spots often appear before the leaf has fully expanded, and as 

 the affected areas are unable to grow, the leaf develops a puckered appear- 

 ance. The petioles and stems are often affected with a more severe 

 necrotic streaking than in the first-generation plants, and the older le ves 





