140 MISSOURI BOTANICAL GARDEN. 



sprayed, experiments were made with various other plants, 

 including beets, grapes, radishes, violets and a species of 

 Mesembryanthemum. On none of these leaves were any 

 intumescences formed, such as appeared on the cauliflower 

 leaves. 



One of the most striking results of the spraying with 

 the copper salts was the different effect of the solution 

 when sprayed onto the leaves in large quantities and in 

 very minute drops. When in quantity, the copper solution 

 almost invariably killed the entire underlying tissue com- 

 pletely, whereas in very fine drops the spray evidently 

 stimulated the leaf tissue, forming intumescences. This 

 result was similar to the one obtained by Dandeno 4 , who 

 found that " dilute solutions applied in drops stimulated the 

 leaf tissue in a ring, whereas if the solutions are concen- 

 trated, the entire area covered by the drop is affected." 



Summarizing the results obtained from spraying, it may 

 be stated: First, that spraying uninjured cauliflower 

 leaves with dilute solutions of copper ammonium carbonate, 

 or with other copper salts, results in the formation of 

 marked intumescences which are particularly prominent on 

 the lower side of the leaves. Second, spraying leaves with 

 dilute solutions of copper chloride, copper nitrate, copper 

 sulphate, and copper acetate, kills the leaf tissue where the 

 spray strikes the same in any quantity. Where very 

 minute drops of the spray struck the leaf surface, small 

 intumescences formed much as they do with copper am- 

 monium carbonate. Third, these intumescences are formed 

 as a direct result of the spraying, and they have no con- 

 nection whatever with conditions which have usually pre- 

 vailed in the formation of intumescences, such as excessive 

 water supply and high temperature. In other words the 

 intumescences form as a result of a direct chemical stimu- 

 lation. Fourth, cauliflower leaves are particularly suscep- 

 tible to such stimulation. Leaves of the grape, violet, 

 radish, beet and Mesembryanthemum did not react. 



