350 
acre were left at the time of the census in December 1920, the 
following results were obtaine 
(1) Trees ees latex into 
the Foe 1428 28% of total. 
(2) Trees vietdiig — oul 2605 =50,, ss 
(3) Trees not yon my 
thin, 
ng Ha. 39 
(4) ‘Trees not tapped (treated 
for brown bast on all 
three segments) - 104 : ae 53 
The planter who furnished these figures states that he has 
been of opinion that on many estates “75° of the crop 
is obtained from 25% of the trees” and these figures 
certainly corroborate his views. It would be interesting to 
know the result of a census taken at a later date, with the object 
of finding out whether the same individual trees are always bad 
yielders; but from Mr. Stafford Whitby’s results given in the 
Annals of Botany (see Kew. Bull. 1920, p. 113), it would be 
expected to be the case. From a similar census made at the 
Rubber Experiment Station, Mooply, during November and 
December 1920 over 1266 trees, the following figures were 
obtained :— 
% of total. 
(1) Trees yielding scrap only - 19-4 
(2) 
Pr » upto oz. of ae - - 29-6 
9 eee ‘; 3 roma % to 1 oz. of latex - 26-8 
is see P 3 4 80 2 OBS. : 7 1750 
(5) »? ” 2” 2 to 3 ozs. as - 4-] 
(6), 3 3s OVer DO. = 2g 
Such information may be profitably borne in mind when 
thinning out. In the case of the first set of figures the 2% 
of trees with brown bast and the 20% not yielding anything 
might be thinned out straight away, provided none recover 
enough to be worth the money spent on them. When 
further thinning became necessary some of the 50% which 
yield scrap only could be removed. In this case, however, 
the trees have already been thinned down to 80 to the acre. 
e above results emphasise the urgent need which exists 
for work to be done on seed selection and plant breeding in 
Hevea which it is intended to carry out at the Rubber Experiment 
Station, Mooply, and elsewhere. 
In reference to Tapping Tests and Bast Examination of 
Hevea Plants from selected seed, Mr. C. Heussen records (in 
Archief Voor de Rubbercultuur June 1921), that on the Bijawak 
Estate a plot was sown in 1915 with seed from the 1914 crop, 
the offspring of four vigorous and high-yielding mother trees. 
In September 1918, 100 eas trees were selected of which 
34 were from mother tree No. 1, 20 from No. 2, 23 from No. 3 
and 23 from No. 4. Up to Boise 1920, five tapping tests, 
