March 22, 1873.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
7 45 
There are some, such as size, colour, etc., which vary in 
individuals of the same species ; others, on the contrary, 
are remarkably constant and definite. Those of the one 
class are of primary importance, and are termed dominant 
characters ; the others are subordinate to them. In 
seeking to find the place of any being or product of 
nature it is necessary to estimate the value of the 
characters which it presents. 
These principles have made a great revolution in all 
sciences which pretend to group the objects of their 
study according to their true affinities. Applied in 
particular to botany, by Jussieu, De Candolle, and Robert 
Brown, they have led to the establishment of groups, 
expressing still very imperfectly the real relations of the 
plants, but which, perfected by later investigation, reveal 
better and better the plan of nature. These investiga¬ 
tions have at the same time shown the preponderating 
value of certain characters, such as the constitution of 
the embryo, that of the seed and of the fruit, and the re¬ 
spective position of the various parts' of the flower, in¬ 
ducing botanists to found their natural groups upon the 
consideration of these floral organs. 
o 
Pharmacologists have profited from these results for 
the solution of two essential questions which presented 
themselves: to discover in a substance the true characters 
which permit the recognition of its nature, and to esta¬ 
blish the origin of such a substance by comparing its cha¬ 
racters with those of plants which might yield it. 
These researches may be applied to products of three 
different orders. One order consists of the liquid or con¬ 
crete juices, which have not preserved any trace of the 
organism that furnished them, and which are thus placed 
outside the domain of botany. Physiology has, it is true, 
already been able to show the manner in which some of 
them have been formed in the vegetable economy ; it has 
thus traced the transformation into gum tragacanth of 
the medullary cells of certain species of Astragalus; but 
in the conditions in which they are presented to the phar¬ 
macologist, it is only by the ordinary physical and chemi¬ 
cal tests that their characters, relations, and sometimes 
•even their origin, can be established. 
At other times the product is an entire plant or part of 
■a plant, containing the characteristic organs of the genus 
and species. It is then a simple case of botanical deter¬ 
mination. If the species yielding the substance be already 
known, it is naturally referred to it; if not, the product 
takes its rank in the genus or family to which it belongs. 
'The groups adopted by botanists thus become the natural 
framework where each medicament finds its place, and 
this is why the writers on materia medica, abandoning 
former errors, have adopted as the most logical arrange¬ 
ment for their works that of the series of natural orders. 
There remains a third group of products, which de¬ 
serves a little longer attention, namely vegetable organs, 
.such as roots, branches, and barks, which do not them¬ 
selves contain the characters employed in the determina¬ 
tion of living plants, and therefore become difficult to 
classify. What part of them will best furnish their im¬ 
portant characters ? Should they be sought in the exte¬ 
rior aspect, dimensions, form, colour, or organoleptic pro¬ 
perties ? Is it not preferable to penetrate profoundly into 
the structure of these organs, and to study their anato¬ 
mical constitution as a means of assisting in this determi¬ 
nation ? The reply cannot be doubtful. The value of a 
-.character may be estimated by its constancy, and that 
which is the most constant in these products is the anato¬ 
mical structure. Varying conditions of the vegetation 
and development of a plant may and do influence consi¬ 
derably the dimensions, colour, and sometimes even the 
taste and smell of its root, bark, and leaves. It cannot 
be affirmed that these influences do not in some cases 
.modify slightly the structure of these organs; but this 
modification would in any case be very slight, and would 
never affect the constancy of these characters, which gives 
them their true value. 
An example will illustrate the services that can be 
rendered to materia medica by anatomical research. One 
of the most difficult questions is that of the sarsaparillas. 
To distinguish among roots so closely resembling each 
Ouher those which belong to the true Sniilax is not 
always easy, and everybody knows by experience how the 
difficulty augments in determining the various commercial 
varieties, and especially in referring them to the plants 
from which they originated. Apply anatomical investiga¬ 
tion to these roots. Nothing is more easy than to 
recognize a true sarsaparilla ; a transverse section suffices 
even to the unaided eye to show a special structure. 
Then if account be taken of the relative size of the zones 
which succeed from the circumference to the centre ; if 
armed with a microscope, certain easily distinguished 
characteristics are studied, the various kinds may be 
determined with a surety that cannot attend an examina¬ 
tion of the exterior characters. Moreover, in comparing 
the structure of Mexican sarsaparilla with that of the 
roots of Smilax medica, their resemblance is seen to be 
striking, and to furnish a nearly conclusive proof of an 
opinion already put forth upon the origin of this com¬ 
mercial variety. 
In the same manner, if it be wished to throw light 
upon the plant which yields the officinal rhubarb, atten¬ 
tion is not confined to the characters of form, colour, 
and odour ; but regard is principally paid to the peculiar 
structure of this root. The same structure not being 
found in any of the species of Rheum to which the drug 
has been successively attributed, it is still looked upon as 
the product of an unknown plant in Central Asia. It 
would be easy to multiply examples, but sufficient has 
been said to show the part that anatomical researches may 
take in the establishment of the essential characters of 
certain products of the materia medica. This idea of 
seeking a means of classification elsewhere than in the 
floral organs has not originated in the present day. The 
first botanists who applied the principles of the natural 
method thought a series of parallel characters might be 
found in the organs of vegetation which could be employed 
to greater advantage. De Candolle laid down this pro¬ 
position clearly in his ‘ Theorie Eldmentaire de la Bote 
nique,’ and sought to apply it in his classification. But 
now, when botanists devote so much attention to vegetable 
anatomy, the theory has become one of the maxims of the 
science, and has extended from the domain of botany to 
that of materia medica. It was applied in France, twenty 
years since, by Weddell, in the difficult study of the cin¬ 
chonas ; in Germany, by Schleiden, in his investigation- 
of the sarsaparillas ; and in England, by Howard, in his 
magnificently illustrated work on various species of cin¬ 
chona. 
The principal phases through which materia medica 
has passed, in becoming a useful auxiliary instead of an 
obstacle to botany, have thus been traced, showing how it 
has acquired from the contact exactitude of description and 
precision of language, and been brought under the influence 
of general laws which have greatly contributed to its pro¬ 
gress. The lesson to the student of the present day is, 
that he should no longer content himself with the study of 
the purely exterior characters of these products, but pene¬ 
trate into the internal structure ; for there he will find a 
new field opened to his energies. 
THE RELATION OF ANIMAL AND VEGETABLE 
OILS TO FIRE. 
BT PROFESSOR ATTFIELD. 
In their relation to combustion, oils of animal origin, such 
as sperm or whale oil, and those obtained from vegetables, 
as olive and colza, differ from mineral oils, by not igniting 
at low temperatures, and in not giving off vapour which, 
when mixed with a certain proportion of air, explodes in 
contact with flame. But in their liability to spontaneous 
ignition when freely exposed to the air under certain con- 
