II 
VANILLA 
37 
Mr. Dupont of the Botanic Gardens there gives an 
interesting account of some experiments in manuring 
which are worth quoting. In five beds the plants were 
grown in ordinary soil, in the others (fifteen) the orchid 
was planted in fibrous roots of the common fern, 
GleicKenia dichotoma, a fern which to a large extent 
in most tropical countries takes the place of the bracken. 
Eighteen months had elapsed since the vanilla cuttings 
were planted. 
They are at present fully grown vines, and those which 
were planted in ordinary soil have developed much less than 
those which were grown from the beginning in fern roots. A 
few of the former possess a yellowish appearance, which is 
striking even in wet weather. In all the basins in which the 
vanilla is growing the roots have developed alongside the walls, 
none having extended as much as one foot from the plants 
towards the centre of the basins. The cuttings had sprouted 
in the proportion of 62*5 per cent in fern roots and of 27 per 
cent in ordinary soil, on the 16 th December, or three months 
after planting. In March 1905 the shoots were 2 ft. long 
in the basins containing fern roots, and only 6 in. in the 
others. It was decided at that time to put a small quantity of 
fern roots on the surface of the basins containing ordinary soil, 
in order to accelerate the growth of vines growing in them. 
In August all the vines were well developed, but on examina- 
tion of the roots it was found that none went deeper than 
6 in. in fern roots, and that in ordinary soil they were fewer 
in number, shorter, and many of them sun-burnt. The aerial 
roots on reaching the soil were found to make excellent growth 
and to produce many rootlets. For this reason it seems that 
much importance should be attached to strengthening and 
protecting the signs of life in the lower part, of the cutting. 
In an ordinary plantation the vines are in great numbers found 
dead or sun-burnt at the base, together with all the roots which 
were produced on that part of the cutting. When this is the 
case the vines produce aerial roots which replace the subter- 
tanean ones, but much of the energy of the plant is lost in this 
new production of roots, and the flowering delayed. 
The action of the sun on the roots is so striking that, in a 
second series of basins to repeat the experiments which are 
found successful in the first, I noticed that the growth of the 
vine is checked when the layer of good loose or fibrous soil is 
less than 2 in. deep. Under these circumstances it seems 
