PLATE 56 
Under surface of a cauliflower leaf showing intumescences produced by the vapor of 
mixed ethyl alcohol and acetic acid (crowngall products). Leaf young when exposed 
and the stomata closed or nearly closed, so that only a very little of the vapor could 
enter. The plants were inclosed in io }4 cubic feet of air space at 20° C. and exposed 
for 30 minutes on September 21, 1916, at ip.m., to the vapors from 10 c. c. of the fluid 
in a porcelain capsule floating in a dish of water at 65° C. Only a small amount of the 
fluid was vaporized but enough to be smelled. Older leaves (half grown) were killed 
quickly in many irregular spots (PI. 55), but leaves of this age did not show any imme¬ 
diate injury. The height of the intumescences may be judged by their shadows. 
Occasionally several are fused. Some are too small to show on the plate. None devel¬ 
oped on the midrib or on the main veins and none or very few on the upper surface. 
Other leaves, where a greater number of stomata may be assumed to have been 
slightly open, showed hundreds of tiny coalescent intumescences, the under surface 
in large patches being one mass of eruptions. Photographed on September 28. X5. 
