114 



acid descicator and weighed. It was found to weigh 4.858 gr., about 

 27^6 of the original weight. In 12. -J p. m. of the same clay ten square 

 pieces of 1 dm 2 , were taken again from each of the same leaves as 

 cut out in the morning. They weighed 17 gr. in fresh, and when dried 

 it was reduced to 5.062 gr., about 30^ of the original one. The 

 increase of the dry weight is probably due to the accumulation of the 

 products of assimilation, as can be observed microscopically that the quantity 

 of starch 1 ] in the leaf is much increased at noon compared with that 

 examined in the morning. 



From above we have the following : — 



10 dm 2 , at 12. J p. m. weighs when dried 5.062 gr. 



„ 6.i a. m. „ „ „ ..4.858 „ 



Increase of dry weight of 10 dm 2 , in 6 morning hours. 0.204 „ 



}} ?; m j) }) lm . ,, ,, ,, 2.040 ,, 



„ „ „ ,, „ „ „ per hour 0.408 „ 



For purpose of comparison I copy the figures arrived at by Sachs' 2 ; in 

 Europe and Costerus 8} in Java for the hourly increase of dry weight of 

 leaves of various plants, taken in lm 2 . 



Helianthus annus. (Sachs) 5, a. m. — 3, p. m ...0.914 gr. 



Cucurbita pepo. ( „ ) 9, a. m. — 12, m 0.680 „ 



Rheum officinale. ( „ ) 6, a, m. — 11, a. m 0.652 „ 



Connarus falcatus. (Costeru?) 6,45 — 12, a. m 0.410 „ 



Erythroxylon Coca. ( „ ) 6,58—12, a. m 0.400 „ 



Sachs found by his well known iodine test (Iod-probe) that between June 

 and July when the nights were very warm, at sun-rise the leaves of Helianthus, 

 Solanum, Nicotiana, Cucurbita, Humulus, Datura, Atropa, Fhaseolus, Jug- 

 hins, \ T itis, Populus, Aesculus were quite devoid of starch. 4) To know 

 whether it in also the case with Nelumbo, I examined the quantity of 



1) Although we can not say that all of the assimilated products once appear in the 

 rm of Btaroh, still its increase or decrease may be used as tlie indicator for the intensity 



of the " Aseiinilatory energy." 



I Brown and Morris, A contribution Ij the chemistry and physiology of foliage 

 leaves. Jonrn. Chem. Soc. Transactions, London. 63 ; 1893. and also, 



A. Meyer, IJber die Assimilation producte der Laubhlatter Angiospermen priauzeu. Bot. 

 Zeit. lhH:>. 



2) Sachs, Wurzburg Arbeiten, Bd. III. 



:5) Costerus, Bach's iodine experiment (Iod prohe) tried in the Tropics. Ann. d. Jard. 

 Bot. d. Buitenzorg. Vol. XII, 1895. 



4) Sach 1 , Wiirzburg Arbeiten, Bd. Ill- 



