66 TRANSPIRATION AND ASCENT OF SAP ch. 



showed the arrival of this stream below, the intervening 

 space of 23 cm. between the bases of D and E was 

 lapped in a cloth and sprayed with boiling water. 

 Meantime the leaves were protected from injury by being 

 covered with damp cloths. The hot spraying lasted 10 mins. 

 After it ceased the cloths were removed from all except 

 the leafy branch D. The transpiration of this branch was 

 thus kept at a minimum during 24 hours, while the supply 

 of distilled water was kept up to flush out the materials 

 exuded into the waterways of the heated region. During 

 this time about 35 c.c. were passed in at the top of B. 

 After this the plant stood in a cool greenhouse under 

 conditions favourable to transpiration. 



Three days later it was observed that the lower leaves 

 of D and a few of the leaves on the lower branches of C 

 were slightly discoloured and curled at the edges. Evi- 

 dently the heating of the part of B had affected not only 

 the leaves above it, but also some of the leaves on a branch 

 springing from below its base. 



After seven days from the beginning of the experiment, 

 the leaves on C and D, which before had shown the slight 

 changes just mentioned, had become quite withered and 

 curled. 



Fourteen days later, i.e., twenty-one from the beginning 

 of the experiment, there were still four living leaves on D, 

 but their veins were coloured red, and the edges of two 

 were discoloured brown. The remaining leaves on D were 

 dry and crisp. On C all the lower leaves had fallen, or, 

 if still attached, were crisp and much discoloured. The 

 remaining upper leaves were apparently still quite healthy. 



The lower killed leaves on C were now removed, and the 

 lower 23 cm. of the branch was killed with hot water in 

 the same manner as B had been, while the healthy upper 

 leaves were protected by enveloping them in a damp cloth. 



Five days after this treatment, all the leaves on C were 

 stained and curled, their cells being evidently dead. 



