VI 
MICROSCOPICAL OBSERVATIONS. 
tissue, in which some few liber fibres are sparsely embedded, and also a number of abnormal concretions. 
A prolongation of a medullary ray seems to indicate the course of an active lateral circulation, and in the 
region of the liber may be seen a few small cells, of a shape that may indicate an approaching change 
to that structure which is seen in the region of the liber in the normal state, as in Plate I. Pig. 1, and 
also in the renewed bark in a state of greater advancement of organization in Pig. 2. 
In this last bark (Pig. 2) we trace all the features of perfect organization, such as may be seen in 
bark in its natural state in Pig. 1. This may be compared with the remarks in the body of the volume (p. 19), 
but in Pig. 8, which is one stage further in the process of renewal, the bark having been tioice stripped 
from the tree, this is much more evident, and I am really astonished at the perfectness and beauty of the 
organization. The bark was rich in quinine, and having probably been exposed to a warm temperature, 
although shielded by moss it also produced cinchonidine. The combined sulphates of these two alkaloids 
amounted to not less than 8‘45 per cent.'* against 5 per cent, from the first crop, represented in Pig. 2. 
The bark of Pig. 8 is consequently very rich in alkaloid, and “ not only is the gross percentage of alkaloids 
larger than in the last decortication, but of this a more considerable percentage consists of quinine, and 
that- less intimately combined with the yellow colouring-matter, so as to be more easily purified.” The 
appearance of the Pig. 8 bark was decidedly more red in the bulk of the sample than that of Pig. 2 ; 
and this feature comes out so strongly in the microscopic sections, as drawn by Mr. West, that I have been 
induced to repeat sections of the bark recently, to satisfy myself whether this was an accidental feature or 
one which might be presumed common to the whole sample. It proved to be the latter ; the sections, even 
the thinnest, exhibiting the rounded cells filled with coloured contents, which characterize Pig. 8, Pig. 3, 
Pig. 7, of Plate II. I mention Pig. 8 first as the one which appears to be most fairly contrasted with 
Pig. 2 of the previous crop of renewed bark. 
The growth must be rapid, since we are told by Mr. MTvorf that renewed bark of one season’s 
growth is “ quite as thick as ordinary bark of two or even three years’ growth.” I should connect with 
this fact the ' existence of the broad band of coloured cellular tissue extending from the liber to the suberous 
envelope. It seems to indicate a vigorous lateral circulation, and perhaps the conversion of some of the 
colouring-matters into resin, for this is favoured by the same circumstances of warm temperature, etc., 
which induce cinchonidine, of which there is a large amount in this bark. The structure of the bark 
(which I thought from my early examinations resembled the granulated flesh over a wound) is in this 
specimen (Pig. 8) singularly perfect, especially when the circumstances of its formation are taken into 
account; and I think the bright colour must be owing to the early stage in which the nourishing sap, 
as derived from the wood, is found, in the full flow of sap and production of alkaloid ; when more fully 
oxidized, it dissolves easily in the caustic ley. 
I found in my renewed experiments with this bark, crystals of some soluble salt of alkaloid, rather 
abundant in the cellular envelope, specially near the corky layer. 
In Pig. 3 (from the same sample of bark) we have a less perfect, or rather a less normal organization, 
the structure between the liber and the suberous envelope being apparently disturbed by the intervention of 
the spiral and reticulate vessels. 
Pig. 7 presents in longitudinal section the structure of the same bark in very ample detail. The 
suberous layer is very thin in this specimen, and the commencing change of the cellular tissue into cork 
is well marked ; also in the portion adjacent to the wood we may notice a rather unusual development of 
the liber-fibres, which occupy, nevertheless, but a small portion of the extent of the bark. 
The whole of the sections of bark in Plate III., with the exception of Nos. 5 and 6, belong to the C. 
succirubra, and illustrate “ the third crop of renewed bark” of which the analysis is given under E. in the 
* f Analysis of Fifth Remittance/ by J. E. Howard. 
f c Report' for 1864-5. 
