444 Mr, D. Thoday. Experimental Researches on [Mar. 1, 



leaves at 6 a.m. and the experimental halves in lots of 15 leaves each at 

 9 A.M. and every succeeding hour till 6 p.m. The correspondence between 

 the results which he obtained on two continuously sunny days is so striking 

 that they deserve consideration, notwithstanding the large errors from 

 shrinkage in area which may be included in them. As Broocks' paper, so 

 far as I am aware, has never been published in any scientific journal and is 

 not readily available, I reproduce his results here. 



In fig. 3 the results of both the experiments in question are plotted ; the 



6 5 n 5 6 Q 12 5 5 q 



A fi ^OON Pn W/CHT A.M 



Fig. 3. — Curves showing variation in relative amount of products of photosynthesis 

 present in leaves of sugar beet at different hours of two continuously sunny days and 

 the nights following them. Constructed from Broocks' data. Ordinates represent 

 excess of dry weight per scpiare decimetre over that at G a.m. when experiments 

 were begun. For (explanation of broken line .see text. 



ordinates represent tlie total accumulation of dry substance since the beginning 

 of the experiment. 



Broocks followed up each of tliese two' experiments by measurements of 

 the loss of dry weiglit between G ]'.m. and midnight, and between G p.m. 

 and 6 A.M. the next morning. His results are added as continuations of 

 the same curve. 



The brok(!n lino re))rcsontK the results for the first experiment, that of 

 August ]8, after making a deduction for tb« (i/ijiftrnii cliaiigo of dry wi'ight 



