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. 

 Tile root on the left is 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- 



