TOBACCO FOR PLANT-LICE. 87 
stroyed, and such treatments are by far the most valu- 
able ones. 
Tobacco.— Several of the most common and often very 
serious organisms may be overcome by vapors with 
which a house may be filled, and the best known and 
the most valuable remedy of this nature is undoubtedly 
29. Galls of a nematode worm on the roots of two tomato plants. 
The root on the left ts unusually severely affected. 
tobacco. The poisonous alkaloids found in the tobacco 
plant are fatal to many insects. The waste parts of the 
plants, particularly the ‘‘stems,’’ are utilized by florists 
and others for purposes of fumigation. 
These stems, which are almost invariably the dried 
mid-veins of the leaves, may be obtained for almost noth- 
