CONTROL OF PLANT DISEASES 



475 



years 1846 and 1864, notwithstanding the fact that the first sulphur 

 treatment for powdery mildew was recommended in 1821 and the first 

 seed treatment for smuts was discussed in 1807. 



Table II. Showing Advance in Knowledge begaeding some of the Chief 

 Diseases of Domestic Animals. The broken upper line indicates vague or indefinite 

 knowledge ; the solid line definite knowledge. The lower broken line indicates partial 

 but unsatisfactory knowledge concerning treatment ; the solid line the possession of 

 facts suflicient for satisfactory treatment. 



Table III. Showino Advance in Knowledge beoabdino sohe or the CHnr 

 Human Diseases. The broken upper line indicates vague or indefinite knowledge ; the 

 solid line definite knowledge. The lower broken line indicates partial but unsatisfac- 

 tory knowledge concerning treatment ; the solid line the possession of facts sufficient 

 for satisfactory treatment. 



