118 
tree is of so much value that it is advisable to give the young 
trees some support. 
The cuttings should be severed as soon as the first two or three 
roots have reached a length of 3 cm., which may take place in 
some fi ix weeks. Aiter removal of the cuttings the cut 
surfaces must be covered with tar or paraffin, and the cuttings 
planted out either as bare stumps or with the majority of the 
leaves removed. It has been found that root growth is stimulated 
by watering with dilute lime water. 
. Heusser goes on to say that this method of selection is 
limited by the physiological “ life’’ of the original tree. For 
the life period cannot be lengthened by grafting or by taking 
cuttings. However young a cutting may be, and however young 
may be the stock on which the graft is made, as soon as the parent 
tree reaches the end of its natural * life,’’ all its descendants will 
die as well. He adds that we have no certain information as to 
the physiological life of Hevea, but that it is to be feared it is not 
a very long one. 
_ The Choice of Trees to be used for Selection.—1. A high and 
constant yield of late is the chief desideratum in a tree to be used 
for selection purposes. On the figures of the daily yield of latex 
taken for several months, and, if possible, on days when an 
abnormally high or low yield is not anticipated (not on rainy 
days), the first selection may be based. Further, the quality ofthe 
tree is judged by— 
2. State of Health. Trees giving abnormally high yields from 
disease must be neglected, or only considered after recovery. 
Gnarled or twisted trees should not be used. 
3. Good Hereditary Qualities. It must be remembered that 
high latex yield depends not only on good inherited qualities, but 
also on such other factors, as soil, age, size, and the competition 
it may have with neighbouring trees. The yield must be judged 
in relation with that given by the trees growing under the same 
conditions, 
producers, to ,use Dr. Cramer’s expression, are veritable 
Ledgerianas ”’ (in Quinine culture C. Ledgeriana is the highest 
producer). 
It must, however, be remembered that there may be species of 
* Whether Dr. Heusser’s Statement has any foundation in fact remains to 
be proved. The only plant in which something of the kind is known to 
occur is the Bamboo, but many cases are i i fro 
some particular ‘sport’ or seedling variety still exist in a healthy and active 
state of growth though the original tree g since died.— Ed. 
+ Tapajoz rubber, Acre rubber. See Cramer Rubber Recueil, 1914. 
