7J 
have done little harm on pure plantations of Hevea, but where Cacao 
is grown with it, the disease is more serious. Close planting adds 
to the risk, and it chiefly occurs in wet weather. It attacks the Rubber 
capsules as well as the bark. 
Cacao is so scantily grown in the Malay Peninsula that it is not 
piobable that here we shall be troubled with this disease, but occa- 
sionally old Cacao trees occur near estates, and in this case the 
planters should keep a watch for the attacks of the Phytopthora.— Ed. 
JAVA GRASS OILS. 
In the C. & D. for December 17, 1910, attention was directed to 
the results of the examination of a number of carefully authenticated 
grass oils from Ceylon, and it is of interest to mention a similar 
investigation of Java grass oils recently carried out by Dr. de Jong. 
The author states that the source of Java citronella oil is the grass 
known in Ceylon as “ Mahapengiri,” while the bulk of the Ceylon oil 
is derived from “ Lenabatu ” grass, consequently he proposes to call 
them A. Nardus , Java, and A. Nardus, Ceylon, respectively : these 
names therefore correspond to Cynibopogon Winterianus and C. Nardus, 
Lena Batu, assigned respectively by Stapf to these two species in Cey- 
lon (Ioc. cit.). The former gives a larger yield of better oil than the 
latter, but requires a richer soil and more careful cultivation. In 
Java the grass is generally propagated by splitting old roots and 
planting the separated parts, so that each has a space about 3 ft 
square to itself. It does fairly well in shade, but better in sunny 
situations. 
De Jong states that the number of crops, which can be taken 
each year, depends on the soil and climate, and no general rule can 
be given. When the first leaf is fully unfolded the following yields 
of oil in c.c. per 100 grams of leaf are obtained : First leaf 7.7, second 
leaf 3.7, third leaf 3.6, fourth leaf 2 6, fifth leaf 2.4, sixth leaf 2.1. The 
leaf sheaths contain much less — viz,, 3*1 c.c. per 100 grams in the 
first, 0.2 in the third, and traces in the fifth. If, however, regard is 
had to the relative bulk of the different leaves, the yields of oil are 
found, for the same number of each of the first four leaves, to be as 
follows .* No. 2.9 ; No. 2, 5i 2 ; No. 3 * 5-8 ; No. 4, 4.7 ; and consequently 
the author recommends cutting when the fifth leaf is well developed. 
The oil is always obtained by steam distillation, and in Java often 
with superheated st°am under a pressure of three or four atmospheres, 
the latter method giving a better yield and being much more rapid. 
It is advantageous to cut the grass into fairly fine shreds before dis- 
tilling. The yield of oil obtained in practice varies from 0.5 to 0.9 per 
cent, of the weight of fresh leaves taken. 
