26 
QUINOLOGY OF THE EAST INDIAN PLANTATIONS. 
presented in my Plates, seems to imply, in this instance, an abnormal state in the newly renewed bark, the 
source and tendency of which is not at first apparent. Though I made perhaps twenty sections of the one 
bundle observed, I failed to find these in other portions, but have again met with similar vessels in a recent 
remittance of the third harvest of renewed bark. In the plates accompanying M. Trecul’s observations 
are seen the adventitious roots produced by a GleditscJiia and by an Ulmvs, in consequence of decorti- 
cation, — showing what might perhaps be called an effort of the plant to regain its normal state and the 
needful channel for its descending sap ; and the vessels I have figured may be a tendency to the production 
of adventitious roots or buds, such as are figured in connection with the paper of the above botanist, where 
the important part assigned to these vessels is clearly seen, and their occasional isolation mentioned as having 
been observed by the author.* 
The Laticiferous Ducts. 
I have hitherto taken little notice of the laticiferous ducts, and yet these must play a not unimportant, 
however obscure, part in the economy of the plant. The latex is one of the products which approach the 
most nearly to those of the animal creation, and it has been compared with the blood ; but in my opinion 
it has more analogy with the biliary secretion, inasmuch as it is a secretion, and not the very life of the plant, 
which latter the blood seems to be in a certain sense to animals, and the chlorophyll to plants, and also to 
some animalcules. 
It may not improbably differ from the surrounding cell-formation in its electro-chemical state, and may 
perform important services to the young developing structures, since it appears to be connected with quick- 
ening and stimulating them ; and in the researches of M. Decaisne it was noticed by him that those portions 
of the cellular structure of the madder through which these ducts permeated were the first to change colour 
from yellow to red, as though by the addition of oxygen gas. I have also noticed that these ducts are the 
first portions of the structure to manifest the alteration when a deterioration takes place in the health of 
the plant. The latex, under these circumstances, changes colour, and gradually turns black. But in what 
relation are we to conceive of these ducts as standing towards the formation of the alkaloids ? 
In the first place, it is certain that, in proportion as the alkaloids become more abundantly developed, 
the laticiferous ducts disappear, as in the fully matured fiat CaUsaya bark, or else become much restricted 
in their size and relative extent and importance, as in the Bed bark ; in which last again the persistence to 
a certain extent of these ducts may be connected with a more abundant development of kinovic acid 
in the C. succirulra than is present in most other barks. 
In the next place, where they do not disappear, as in some inferior barks, such as the C. ovata, an 
inferior production of alkaloid occurs, and of this poverty there is no more certain sign than the occurrence 
of wide, open, laticiferous vessels ; further, that in the allied genus of Ladenbergia (or Gascarilla), in which 
these assume large proportions and are permanent, it is kinova-bitter alone that is predominant. Large 
development of these ducts, therefore, indicates large production of kinova-bitter, and diminishing and dis- 
appearing laticiferous vessels indicate abundant formation of alkaloid. 
The conclusion, therefore, to which I arrive is, that laticiferous ducts exist for the secretion of kinova- 
bitter, — at least in the present families of plants under review. On the other hand, their disappearance is 
connected with the change of the kinova-bitter or its elements into alkaloid ; and that not in these ducts, 
but rather in the parenchymatous cell formation. 
* “ Stir 1’origine des bourgeons adventifs” (Ann. des Sc. Nat., tome yin. 1847). “Dans les bourgeons adventifs, ce sont des 
vaisseaux reticules gui deviennent ponctues, qui se montrent d’abord.” (Ann. des Sc., tome xvii., ibid. p. 268; see also tome viii. 1847, 
p. 290.) “ J’ai vu aussi quelquefois des vaisseaux isoles, non accompagnes des tissus qui entourent ordinairement ces organes, 
repandues au milieu des fibres du liber.'” (Ibid, tome viii. 1847.) 
