CH Vm.] THE DISEASES OF PLANTS. '271 



have since been made on its rapid and brilliant 

 progress. If a sulphate, an acid, or a metal is 

 mentioned, a chemist immediately has a definite 

 idea of the nature and properties of the substance 

 alluded to, but if a loam or marl is spoken of, 

 would any t^ro cultivators of the soil agree in their 

 idea of what description of earthy compound was 

 intended? To make it well understood, a long 

 detail must be added, and nothing checks the im- 

 parting of knowledge more than the person capable 

 of imparting it being conscious that he must define 

 every term as he goes on, and that even then it is 

 doubtful whether he shall succeed in making himself 

 intelligible. The veiy name (ambmy) usually ap- 

 plied to the disease which is the subject of our present 

 consideration, is another proof of the necessity of a 

 reformed horticultm^al and agricultural nomenclature ; 

 for, LQ Suffolk, the same title is given to another dis- 

 ease, which merely affects the leaves of the tui'nip. 



Sir Joseph Banks, Mr. Baker, of Norfolk, and 

 others, agree that marl is the best preventive of am- 

 bury, and another evidence of the efficacy of appli- 

 cations to the soil, is afforded by a gentleman in 

 Holdemess, a Mr. Brigham, who had a highly ma- 

 nui'ed clayey ridge, which he had levelled the year 

 before, and which grew turnips entirely free from the 

 disease, whilst, in the natural rich loam of the field, 

 they were much infected. 



