3 i6 
possible for the individual to remain in the room. It is probable, 
however, that cones made of powdered basil would, when burnt 
have the effect of driving mosquitoes away, and to this extent might 
be found useful. 
In conclusion I wish to express my indebtedness to Dr. Hood, 
Senior Medical Officer, for his assistance in performing the experi- 
ments and verifying the results. 
W. T. PROUT, 
Principal Medical Officer, 
Sierra Leone, 
Times . 
PARA RUBBER IN SELANGOR, 
By S. Arden. 
Experimental Plantation’s Office, 
batu TIGA, 
Federated Malay States, 
rjth August , /po?. 
In a report on Hevea brasiliensis published some months ago, 
the question of extracting the latex, and the effect of wounding on 
the flow of latex was gone into, and I now intend to give the 
results of some further experiments made with the object of veri- 
fying the results which appeared in that report. 
The aim of the planter is to produce the maximum of latex with 
as little injury to the tree as possible and at the least possible 
expense. It has previously been pointed out that this tree is, 
fortunately, very hardy and appears to be little effected by the 
wounding necessary to obtain the latex, so that if ordinary care 
is exercised little or no injury results; but a point which I think 
has not yet received the attention it calls for when deciding what 
style of incision should be practised, is that of the necessity of 
economising the available tapping surface. Previous experiments 
have shown conclusively that the first 3' of the trunk from the 
base, contains the largest amount of latex, while if the tapping be 
extended beyond 6’ from the base, the quality of the latex de- 
creases as well as the quantity, being much poorer in the per- 
centage of caoutchouc and containing a larger proportion of resin, 
and the rubber is therefore not so elastic. It will be seen, then, 
how very essential it is to economise this somewhat limited tap- 
ping area, for no matter how skillfully the wounding is accom- 
plished the result will be a rough and broken surface which will 
be found difficult to work, while the disconnected tissue will un- 
doubtedly interrupt the flow of latex if tapping operations are 
repeated before cicatrization is complete. 
The necessity of taking advantage of what is termed “wound 
effect” was shown in the report previously referred to, and I 
recommended that the wounds should be re-opened by taking off 
