KUNKEL: VIRUSES 91 



plants a strain was obtained that stimulated longitudinal growth and checked 

 transverse growth. This caused a spindling witches' broom type of growth. In 

 tomatoes with the spindling strain no flower buds were produced except shortly 

 after infection. The flowers that were produced usually were not more than two 

 to three times the size of normal flowers. Between these extremes in which long- 

 itudinal growth was almost entirely stopped but transverse gi-owth stimulated, 

 on the one hand, and in which longitudinal growth was greatly stimulated but 

 transverse growth severely checked, on the other hand, were strains that 

 caused intermediate effects. Some of these are shown in figure 5 where tips 

 from five different diseased tomato plants are pictured. The tip at the extreme 

 right is greatly shortened and thickened ; that on the extreme left is tall and 

 spindly. The three types shown between these exhibited intermediate ef- 

 fects. The virus obtained from most diseased cranberry plants caused the 

 symptoms shown by the tip in the center of the picture. This is the typical 

 big-bud type of top where flowers are large and malformed and where con- 

 siderable numbers of secondary shoots are produced. When scions from plants 

 affected in this way and scions from plants showing the two extreme effects 

 were grafted to healthy tomato plants, each came down with the type of disease 

 characteristic of that shown by the plant from which the scion was taken. When 

 the two extreme types were transmitted to periwinkle plants, they caused simi- 

 lar variations in symptoms. The virus that depressed longitudinal growth but 

 stimulated transverse growth in the tomato caused the production of short thick 

 tips but very little chlorosis or stunting of leaves when taken to periwinkles. 

 The virus that stimulated longitudinal growth but depressed transverse growth 

 in stems of the tomato produced similar effects in stems of periwinkles. In 

 leaves it caused a marked chlorosis and narrowing. When the virus causing 

 typical big-bud in tomato was taken to periwinkle, it caused the production of 

 green malformed flowers such as are shown beside normal flowers in figure 6. 

 When scions from periwinkles showing the dift'erent types of effects were 

 grafted to healthy periwinkles, each transmitted the disease characteristic of 

 the plant from which it was taken. While it has not been proved that these 

 different types of disorders are caused by strains of the cranberry false blossom 

 viruS;, this seems likely. When the common type of false blossom virus was 

 transmitted to the composite, Calendula, it caused the production of malformed 

 green flowers such as are pictured in figure 7 beside a healthy flower. Another 

 plant in which false blossom virus caused gigantism in flowers was Nicotiana 

 glittinosa. An early stage in the development of giant sepals is shown in figure 

 8, a late stage in figure 9. The blossoms at the left in both figures are normal ; 

 the others are diseased. Malformed leafy structures are shown protruding 

 from some of the diseased flowers in figure 9. At the same time that the virus 

 caused enlargement of flowers, it produced dwarfing of leaves. 



