18 Dr. Hamilton on the 
an ingredient in one of the most deadly of the toxiques of 
South America; the Galega toxicaria, and a plant of which I 
have never been able to obtain any true account, which the 
Carribs of St. Vincent were said to employ, in a somewhat 
different manner, for the same purpose, under the name of 
Wonga root. From the similarity of the effect produced by 
all these various substances on the animal economy, it is not 
unreasonable to conjecture that this uniformity of action 
arises from the uniform presence of the same active principle 
in each, analogous to the morphine, quinine, tannin, &c., 
which are found to pervade a variety of dissimilar plants, 
communicating to them, however, a similarity of properties 
more or less decided according to the degree of concentra- 
tion in which it exists in each. Hence it might be worth 
while to subject them all to the test of medical experiment, 
in order to determine how far their active properties are capa- 
ble of being rendered subservient to the wants of mankind. 
In the only instance in which I have had an opportunity 
of witnessing the powerful effect of the dogwood as auxiliary 
to the fisherman, it was the bark of the roots, and not the 
leaves and young branches, which were employed. This 
bark was gathered at the season of flowering, and at the 
lunar period at which, according to the well-ascertained law 
of intratropical vegetation, the juices of the plant were in the 
highest state of activity, namely, the full moon in April. To 
those whose acquaintance with the phenomena of vegetable 
life is limited to the temperate zone, the idea of lunar influ- 
ence upon the circulation of the sap may appear more vi- 
sionary than correct; but to those who have resided for any 
time within the tropics, the fact is perfectly familiar, and the 
importance of strict attention to it fully known: the influence 
of the lunar phases on the sap in trees is such as to render 
the strictest attention to the state of the moon at the time of 
felling timber necessary, if the timber is desired to be dura- 
ble. The West Indies abound in the most valuable hard 
woods, such as the Zygophyllum arboreum, or Guayacan 
tree, which, if cut between the full and new moon, when the 
sap is dormant or descending, are almost indestructible; but 
which, if felled between the new and full moon, when the sap 
has begun to mount, will infallibly begin to decay before the 
expiration of ten years, or even a shorter period. Even the 
fact alluded to by the Roman poet of the influence of the 
phases of the moon on animal life, where he says, 
‘«* Lubrica nascentes implent conchylia Lune,” 
is perfectly familiar to the West India planters, who never 
