PLATE 2 



I . — Soil temperature tanks used in the temperature experiments. The water surface 

 was later covered with sheet metal and asbestos board. 



II, III. — Influence of soil temperature on the growth of tobacco: 



lA, infested soil, i7°-i8° C. 



2 A, infested soil, 2o°-2i° C. 



3A, infested soil, 23°-24° C; 



4A, infested soil, 25°-26° C. 



5A, infested soil, 28°-29° C; 



6A, infested soil, 3i°-32° C; 



iB, uninfested soil, i7°-i8° C; 



2B, uninfested soil, 2o°-2i° C; 



3B, uninfested soil, 23°-24° C; 



4B, uninfested soil, 25°-26° C; 



5B, uninfested soil, 28°-29° C; 



6B, uninfested soil, 31 "-32 ° C. 

 IV. — Influence of different soil temperatures on root development: 



lA, uninfested soil, i7°-i8° C; 



iB, infested soil, i7°-i8° C; 



2 A, uninfested soil, 2o°-2i° C; 



2B, infested soil, 20°-2i° C; 



3A, uninfested soil, 23°-24° C; 



3B, infested soil, 23°-24° C; 



4A, uninfested soil, 25°-26° C; 



4B, infested soil, 25°-26° C; 



5A, uninfested soil, 28°-29° C; 



5B, infested soil, 28°-29° C; 



6A, uninfested soil, 3i°-32° C; 



6B, infested soil, 3i°-32° C. 



