138 HENRY G. SMITH. 
No.6. Leaf 127 mm. long, 24 mm. wide, dull green above 
and below, midrib, edges of leaf and petiole red. 
A terminal shoot corresponding with No. 1 was crushed, 
Spread out as much as possible, and treated with ether. 
(The elastic substance is quite insolnble in ordinary ether). 
A white powdery substance was extracted in small amount; 
this melted at 222° C. 
The elastic coating was then stripped from some leaves 
corresponding to Nos. 2 and 3, and a small amount of the 
white powder soluble in ether was obtained; it melted 
at 225° ©. <A single leaf corresponding to No. 4 was 
treated with ether, it gave a quantity of white powder 
which melted at 215° C. The next leaf No. 5, gave a 
larger amount of the white powder to ether, this melted 
at 205 C. No.6 leaf gave even a larger amount of powder 
to ether; this melted at 195° C. No. 10 leaf on the same 
branchlet, gave about the same amount of powder to ether 
as No. 6; this melted at 195 OC. A leaf taken from the 
lower portion of the branch did not contain so much powder 
removable by ether, but it melted at 195° C. also. 
These results were all obtained at the same time and are 
strictly comparable. The contact with ether was three 
minutes in each case. It is thus evident that as the leaves. 
grow older, the white powdery substance (which is also 
present in the earliest shoots) increases in amount, the 
caoutchouc diminishing at the same time. This alteration 
was proved in another direction. After removing the 
substances soluble in ether from the shoots and young 
leaves they were spread out in the sun and air for 5 weeks. 
On extracting with chloroform for 5 days the “‘rubber”’ 
obtained was more soft and sticky than that extracted 
from the fresh material; it was also less elastic. When 
treated with melted sulphur it vulcanized fairly well, and 
