462 
Latex is very soon renewed after a period of tapping, but the pro- 
duction of rubber (caoutchouc) is a very much slower one. Thus in 
a trial of the spiral method of tapping on the largest tree in the 
Garden (girth at 3 ft. from ground 9' 4") we obtained from the first 
period tapping 531 fluid ozs. of latex * giving 9 lbs. of rubber and from 
the second period of tapping one month afterwards 433 ozs. of latex 
giving only 4 lbs. 15 ozs of rubber (See Spiral Tapping) the ratios of 
caoutchouc to latex comparing as 3 fluid ounces to one ounce dry 
rubber, as against 5 T ^ fluid ozs. to the same amount of rubber. It is 
therefore of the greatest importance to the cultivator in tapping to 
avoid tapping at the wrong season when he is very liable to interfere 
with the special physiological processes in the tree then performing 
their functions. The periods of these processes cannot be controlled 
or modified, the cultivator will therefore have to adapt his work so- 
as not to clash with them. The bark of the tree does not recover as 
well from wounds during the resting period between December and 
March, nor does it appear that the return of caoutchouc is as good. 
Further experiments we hope to carry out next year on this most 
important subject which will probably furnish the key to the whole 
of the rationale of the rubber industry. Rapid and good renewal of 
the bark is very necessary not only to protect the wound fiom in- 
jurious attacks of fungi but to increase the production of caoutchouc. 
Too frequent or prolonged tapping is not only injurious but. pro- 
duces a laiex very inferior in its rubber-producing qualities. This can 
only be due to actual bark injury. The experiments made on an old 
stump in the Botanic Gardens seem to show this and to throw some 
light on the origin of rubber in the plant. A figure of this stump is 
given herewith. It was a tree of considerable size, measuring 40 
inches in girth at three feet from the ground when the top was 
broken off accidentally some ten years ago. It then commenced to 
die from the top and till a few years ago produced at intervals 
shoots bearing a few leaves, the remains of the last of which can be 
seen just above the Polyporus fructification growing on the decay- 
ing wood. It had by this year died down to within two feet of the 
ground and wa c tapped by single incisions at the base, from which 
were obtained 31 oz: of dry, and very strong rubber. The bark was 
renewed in a 4 ew months, and w r as again found to contain rubber. It 
is long since there have been any leaves on the tree and it is clear that 
only the bark and roots have played any part in the renewal of the 
latex in the stump. 
The experiments made this year show that although in over-tap- 
ping latex is renewed in the bark quickly, caoutchouc takes much 
longer to produce, though it does not seem in the worst cases ever 
to he entirely absent from the latex. 1 he caoutchouc seems un- 
doubtedly *to be directly or indirectly produced from the roots but 
as the only injury to the tree in tapping is caused to the bark ot the 
trunk it seems clear that it is the bark injury only which reduces 
the amount of caoutchouc in the latex for it does not seem probable 
that the roots can be affected by the bark injury. 
* Including the same quantity of added water at each period. 
