42 ANALYSIS OF CHINCHONA 
in full flow, being the period when the plants contain the greatest pro- 
portion of moisture. 
The object in submitting these specimens was to ascertain how far 
this condition affects the yield of alkaloids. The last supply of bark 
submitted to analysis by Mr. Howard was cut when the sap was be- 
ginning to rise. A further supply will be forwarded in the dry sea- 
son, when the plants are at rest, and this will be sufficient to enable 
Mr. Howard to form an opinion of the most advantageous time of 
collecting the bark. Mr. M‘Ivor is inclined to think that the bark 
should either be cut in the middle of the dry season or in the spring, 
as the sap is beginning to rise; these seasons are also most favourable 
for drying and preserving the bark. 
The plants under culüvation have given unmistakable signs that 
they do not require so moist a climate as they are represented to enjoy 
on the Andes. This season at Neddivuttum has been unusually wet, 
and several of the Grey Bark plants have suffered in consequence. 
The way in which the continuous rain seems to affect the plants is by 
throwing a constant stream of water down the channels of the leaves, 
which, resting in the axil, causes the bark there to decay; this decay 
is communicated to the young growing wood, and, ultimately, to the 
pith ; the decay having once reached the pith, the rain-water finds its 
way into the centre of the stem, and in this way affects the health of 
the plant. A specimen of the wood of Chinchona micrantha was for- 
warded for Mr. Howard's opinion on the subject. The Red Bark, 
Crown Barks, and Yellow Bark, do not suffer from this cause, ap- 
parently because the petiole of the leaf in’ these species is more 
rounded, and, consequently, it does not conduct and deposit the water 
in the axil of the leaf, as is the ease with the : Barks. 
Specimens of Chinchona Barks, et 
No. 1. Chinchona succirubra, Red Bark from phon of twenty-two 
months' growth. 
2. C. succirubra, Red Bark from plants of eighteen. months’) 
growth, thickened by being covered with moss for three: 
months. | 
3. C. succirubra, Red Bark from branches of eighteen months’ 
growth and under. 
4. Renewed bark of O. succirubra, the centre part. being the bark 
renewed a second time, 
