MISSOURI BOTANICAL GARDEN BULLETIN 109 
growth frequently noted in tropical species; that is, no 
annual rings are visible. As might be expected, the per- 
centage of actual fibre per cubic foot is very small; in 
other words, the wood is made up of very thin cell walls 
filled with air, giving it an extremely spongy texture. It 
has very little, if any, true wood fibre, as the cells are almost 
parenchymatous. For so light a wood, it appears remark- 
ably strong but from information received, its lasting power 
is very slight. It absorbs water rapidly, and, unless impreg- 
nated in some way to protect it against water absorption, will 
become waterlogged very quickly. However, it is extensively 
used when thoroughly impregnated with paraffin. 
Balsa wood has only recently come into commercial use 
in the United States, being imported chiefly from Costa 
Rica. It is now being used very largely after treatment 
with paraffin for making the floating parts of modern life 
preservers and for constructing life rafts. (A complete life 
raft of Balsa wood is exhibited in the Museum at the Garden.) 
It is also being employed by the Government for buoys and 
floating attachments to signals. Another use to which it is 
being extensively introduced is for interior linings of re- 
frigerators. Owing to its extremely porous nature it acts as 
an excellent insulator against heat and cold, and from some 
tests recently made with a specially constructed Balsa wood 
box, it was found that when used as a fireless cooker, articles 
put into the box at night retained the heat until the follow- 
ing morning; on the other hand, a piece of ice remained in 
the box from five to six hours during the middle of a very 
hot day. 
It is probable that, with a wider recognition of the peculiar 
characteristics of the wood, many other uses will be found 
for it in the near future. 
VANILLA 
The fine specimen of the vanilla orchid (Vanilla plan- 
folia) growing in the epiphytic orchid house is now in bloom 
and for the next few weeks will be an object of particular 
interest. The vanilla is probably the only orchid of great 
economic importance. It is a native of Central America but 
is grown extensively in the Seychelles Islands, Réunion or 
Bourbon Island, and the Society Islands. So important has 
the industry become that in the small island of Tahiti the 
crop for 1897 was valued at nearly $175,000, and in the 
Seychelles Islands the annual yield was estimated at 
$246,000, while as early as 1892 the industry yielded to 
Réunion over half a million dollars. : 
