92 Dr. H. T, Brown and Mr. F. Escombe. [Jan. 9, 
Table III.—Coefficients of Absorption and Transmission of the Radiant 
Energy of Sunlight for Leaves of Different Plants. 






| Coefficient Cosmiclae 
| Plant of transmission 
of absorption (qa). 
| | (1 -a). 
| 
PL CIAOTLIUUS CNNINUS, ala jlo tae (cs eee 0-686 0°314 
HAO) VOOMLUNT GV V-CULICNUN acura teceates ee eee 0°647 0°353 
- SACRALUMENSE Ui asic wate scene 0°69] 0-309 
| Petasites officinalis ..sicese. soak gachr teas 0°728 0-272 
| Salphium terebrinthacewm ..........csccceeeees 0°699 0°391 
WRAL CLINTON UI US sa Reese < rshcter «Se hee 0:728 0:272 
beZerbascum olympicua 2050. wee saeco 0°758 0:242 
PSCNCCIONGTONUL) OUUWS xe eean ciate Rete a0 ciacee eevee 0°774 0-226 


The following table gives the results of two different series of observations 
of this kind made on leaves of Senecio grandzfolvus :-— 
Table [V.—Coefficient of Absorption of the Radiant Energy of Sunlight for 
Leaves of Senecio grandifolius taken from the same Plant in Serial Order. 




Series A. Series B. 
| Coefficient of Coefficient of 
| absorption. absorption. 
Leaf 1 (youngest mature leaf) 0-750 0°776 
ea ee er 0-748 0-771 
We Ch i pe ore 0-757 0-763 
| Bh 08 SAR Eee eee Beamon 4, NARA nt aD 0:762 0:°784 
ia Tee Gy Pier aves BY Mobos heh ie dh cn 0-793 0-776 
| SE rR eI fhe i Nedln Oa 0:778 ae 
It will be seen that the variations in the values of the coefficient of absorp- 
tion in this plant are not large, and that such as they are they show little or 
no relation to the age of the leaf. 
In another similar series of experiments with Polygonum Sachalinense, 
recorded in the following table, there was some indication of a slight increase 
of the coefficient of absorption with the age of the leaf. 
