70 ' Dr. Hamilton on the 
of an ash colour, marked with irregular longitudinal furrows, 
and separating from the inner or thicker coat, which had 
more of a ligneous texture, or any attempt at breaking the 
bark, by bending the fragment marked a, exhibits both the 
inner and outer coats of the bark united; on fracture, the 
smell was agreeably aromatic, and the taste not unpleasantly 
bitter. I failed in my expectations of obtaining a satisfactory 
report of its effects from Dr. Cookworthy, and could only 
learn from him, in conversation, that it was as effectual in 
arresting the progress of intermittents as the cinchona; but 
the bulk of the dose rendered its exhibition objectionable, 
especially since the introduction of quinine, a few grains of 
which produced all the effects of as many ounces of either 
the Peruvian or Malambo bark. I urged him in vain to get 
his brother to analyse a portion, and “determine the nature 
and quantity of its active constituents; and I found that, by 
‘trusting to others, I had again lost the opportunity which 
this second supply afforded me of investigating its useful 
qualities.. I had, however, retained one piece of the bark, 
which I treasured up, in the hope of some future opportunity 
offering for getting it analysed; and this piece I shall gladly 
place at the disposal of the Society. 
I was equally unsuccessful in my applications to Mr. 
Watts for specimens of the plant which produced it; and 
hence I am unable to throw the smallest light upon the genus 
to which it belongs, or advance anything beyond the merest 
conjecture. ‘That it does not belong to any of the true cin- 
chonas, which differ from the Exostemas in having their 
stamina included, seems probable from HumsBo.pt’s obser- 
vation, (Pers. Narr. vol. iil. p. 29, note,) that almost all the 
cinchonas of the inferior regions are Exostemas, not true 
cinchonas, the properties of which differ considerably from 
those of the genuine cinchonas of the Andes; while, from his 
observation of the fact of his not having found a single 
specimen of Exostema during his long abode on the coast of 
Cumana and Caraccas, the banks of the Apuri, the Oronoko, 
and Rio Negro, in an extent of country of four thousand 
square leagues, it seems equally improbable that it belongs 
to the genus Exostema. It is probable therefore that it 
belongs either to the febrifuge bark-tree described by Dr. 
Hancock, the Cusparia of the banks of the Oronoko, the 
Machaonia, the Cuspa of Humboldt, a nondescript plant, 
the inflorescence of which Humboldt has never been able to 
procure, notwithstanding its blossoming at the end of No- 
vember, and being abundant in the province of Cumana; or 
perhaps a new and distinct genus. 
