1896] A RUST AND LEAF CASTING OF PINE LEAVES 451 
ends of the diseased cut leaves were more securely closed, so 
that they dried out only a little more rapidly than the healthy 
ones, This experiment shows that cutting off the diseased parts 
reduces evaporation to the normal amount. It appears there- 
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ue Diagram showing evaporation from healthy and diseased leaves from which 
the tips had been cut. 
ne that as soon as the fungus ruptures the cortical tissues’ of 
® leaves nor mal evaporation is increased about one-fifth. The 
Physiological significance of this fact is great, as it affects the 
“atte economy of ithe plant. 
out entering upon a discussion of al 
pe it may be said that this constant loss © 
.. nnot be supplied by the conductive tissue. = 
is . of water in the cells is therefore eee 4 
wed by loss of turgidity, cessation of growth, 
| the processes 
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