28 Mr. D. Thoday. Experimental Researches 07i [June 11, 



16 per cent, in width in tlie 5 minutes elapsing between the measurements 

 made at 10.50 and 10.55. It is highly probable that with more accurate and 



X.o, 



PercenDag'e decrease 



12 3 4 5 



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--Swn Chroug+i thin 





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PercenbaR'e decrease 



Fifi. 0. — Curves Hhowiii;,' tln' rapidity of reaction of a leaf of Ihi'mviltxix inunni.t to 

 varyiii{{ illuiiiiiiatioii, on AuguKt 1, 1!)0H. 



AlwciHH!!' are percentage differences fnnn the linoai' diniciisions in the early 

 inortiiiit; of (lie previoUH day. (!urveis A, l>, (!, I'efer respectively to nieastireinents 

 across th(! h-ft and i ij,dit half-leaves, and a measureniont along the midrib. 



