The Laticiferous System of Hevea brasiliensis 
and its Protective Function. 
BY 
A. SHARPLES. 
E XPERIMENTAL work designed to test the suggestions put forward 
to explain the significance of the role played by the laticiferous system 
of latex-bearing trees has seldom been attempted. Of the suggestions 
long standing, the one that latex exercised a protective function against 
fungus and insect attacks has received popular acceptance amongst the 
rubber-planting community of the Middle East. M. George Vernet 
brought forward evidence indicating that small boring-beetles, e. g. Xyle- 
boras parvulus , Ptorelephia melaneura , could penetrate the bark of a healthy 
rubber tree without being killed by the latex, but the general opinion was 
stated by Pratt: 1 ‘In most cases of insect attack’ (with special refer¬ 
ence to shot-hole borer \Xyleborus parvulus ]) ‘ on Hevea brasiliensis which 
have been personally observed it would appear that a fungus disease pre¬ 
ceded the insect attack.’ Thus it would appear that a healthy tree with 
a sound laticiferous system could not be penetrated by insects ; the latter 
are only capable of penetrating into the wood when the laticiferous cells are 
killed previously by the fungus hyphae. 
The method of tapping Hevea brasiliensis and the wound-response 
exhibited is universally known and needs no further description. Many 
methods of artificially stimulating this wound-response and so obtaining 
a correspondingly greater yield of latex have been suggested and tried on 
the plantations. One method, recently given much publicity and tried on 
a large scale, was suggested by Dr. Fickendy, late Director of Agriculture 
in Samoa. He applied for patent rights, and claimed an increase yield 
of 50 per cent. 
His method consisted of scraping the bark over the proposed tapping 
area some time previous to the tapping. When the outer corky bark is 
gently scraped away with a blunt instrument, the cork-cambium (phellogen) 
is exposed as a green layer overlying the cortical cells. Fickendy’s sugges¬ 
tion was to scrape away the corky cells, exposing the phellogen, but leaving 
the latter intact. The response to the stimulus of scraping should be 
a substantial increase in the yield of latex. 
1 Pratt, H. C.: Report of Director of Agriculture, F.M.S., 1914. 
[Annals of Botany, Vol. XXXII. No. CXXVI. April, 1918.] 
