INTUMESCENCES. 



135 



Plant No. 2. 50 per cent, of glue. The same condition as noted for 

 the first plant was true here. 



Plant No. 3. The -plant sprayed with Bordeaux mixture showed no 

 change whatever under the sprayed spots. 



Plant No. 4. The plants sprayed with Bordeaux mixture and glue 

 showed no change whatever. 



Plant No. 5. Leaves sprayed with ammonium copper carbonate showed 

 a discoloration of the leaves, not only under the immediate spot where 

 the drops of solution struck the leaves, but extending considerably be- 

 yond these spots. On the lower side of two of the sprayed leaves, small 

 warts were forming in considerable numbers, some of which had already 

 broken through the epidermis. 



Plant No. 6. The same condition as noted for plant No. 5 was true in 

 this case. That is, on most of the leaves which were sprayed warts were 

 forming on the lower surface. 



■ 



It appeared from this experiment that the intumescences 

 were not formed by the glue, or by the Bordeaux or by the 

 combination of glue and Bordeaux mixture. It further- 

 more appeared that the glue was not a necessary element 

 to their formation, when mixed with ammonium copper 

 carbonate, for the ammonium copper carbonate produced 

 the intumescences without the glue addition. The plant* 

 were examined again after 11 days and no change what- 

 ever had taken place, except in the case of plants sprayed 

 with ammonium copper carbonate and its glue addition. 

 By that time the plants which had been sprayed with am- 

 monium copper carbonate alone showed a great number 

 of swellings, particularly on the lower surface of the leaves. 

 Where the spray struck the leaves in large blotches, the 

 eruptions took place chiefly around the edges of the sprayed 

 spot. In the case of the plants to which the glue had been 

 added, the eruptions were practically confined to the small 

 spots, for with the glue addition the spray came out very 

 fine. The eruptions in this case were generally not more 

 than two to three millimetres in width. 



Several experiments were then made with ammonium 

 copper carbonate alone and it was found in practically 

 every instance that within five or six days large numbers 

 of intumescences could be produced as a result of the 



s 



