1910.] Vegetable Assimilation and Respiration. 427 



Experiment 3. — July 23, 1909. Five leaves gathered 5.30 a.m. Experimental 

 halves exposed in the open air 8.30 a.m., removed to greenhouse at 10 a.m. 

 owing to strong wind. Experiment closed 3.45 p.m. ; duration, 7 j hours. At 

 first bright sun, clouded over gradually, but brightened again to fine sunny 

 afternoon. 



Table III. — Asymmetry error as in Expt. 2. 



Leaf. 



Rate of increase in 

 milligrammes.* 



Condition of exjierimental 

 half-leaf. 



10 



17 -1 



Turgid. 



11—14 



5 -3, 4 -0, 4 -3, 7 -8 



Flaccid to variable degrees. 





• 





* The rate of increase of dry weight is given throughout in milligrammes per square decimetre 

 per hour unless otherwise stated. 



Uxperiment 4. — August 6, 1909. Four leaves gathered 7 a.m. Experi- 

 mental half-leaves set up under water-pressure of about ^ metre, and 

 exposed at 9 a.m. Water-pressure increased to 1-^ metre at 9.40 a.m. Set up 

 canvas screen at 2 P.M. Experiment closed 5.10 p.m. ; duration, 8-^ hours. 

 Bright sunshine throughout ; very little wind. Sun temperature, 27° to 

 29°-2 C. 



Two pieces were cut from each half-leaf in the cases of Leaves 15 

 and 17, and were dealt with separately. Each pair of corresponding 

 pieces from control and experimental half-leaves thus afforded a measure- 

 ment of the rate of increase in the region of the leaf from which they 

 were cut. 



Table IV. — Asymmetry error : average about +0'8 milligramme; maximum 



about +1-6 milhgramme. 



Leaf. 



Rate of increase in 

 milligrammes. 



Condition of experimental half -leaf. 



/ 15, tip 

 \ 15, middle 



16 

 r 17, tip 

 \ 17, base 



18 



15 -5 

 14 -1 

 8-0 

 8-5 

 4-1 

 -0-5 



"1 Fairly turgid, slightly limp about 

 J mid-day. 



Slightly limp, occasionally more limp. 



Ditto. 



Gradually more flaccid till drying. 

 Flaccid throughout. 



In this experiment none of the leaves remained perfectly turgid throughout 

 the experiment, and none has increased in weight at so high a rate as the 

 turgid leaves of Expts. 2 and 3. 



It was observed that the part of the leaf towards the base and furthest 



