Sept. 17, I9I7 Mosaic Disease of Tobacco 631 



solanaceous plants, appears to be an efficient carrier of the infective 

 principle of the disease. 



(10) Red spiders, which rarely attack tobacco in the greenhouse have 

 consistently given negative results so far as the transmission of the 

 disease is concerned. White flies, which are often very troublesome 

 pests upon tobacco in the greenhouse, do not appear to be actively 

 concerned with the transmission of the disease. 



