460 
PHARMACEUTICAL MEETING. 
The climate of Great Britain and Ireland is insular, i. e. the summers are 
cool and the winters mild, while the broad features of the North American 
climate are, that its summer is in general cooler than that of Europe, under 
corresponding latitudes and distances from the sea, and that its winter is very- 
cold, i. e. it has a continental winter climate and an insular summer climate. 
The extremes of temperature for the year are greater in North America than 
in Europe, and that difference increases with the latitude. Hence on this ac¬ 
count, and also because the amount of heat which a plant receives during the 
period of its greatest activity is of chief importance, we should attach more 
value to the monthly than to the annual isotherms.* 
The mean annual temperature of Dublin is 50°, and its mean summer tempe¬ 
rature about 60°, or 58°-6 according to a series of observations extending be¬ 
tween the years 1792-1852. By comparing the mean temperature of Dublin 
for the months of May, June, July, August, and September, with the course 
of the isothermal lines for these months respectively, as laid down on Dove’s 
charts, we see at once that, on the whole, the mean summer temperature of the 
United States is considerably higher than that of Dublin. 
July is the warmest month from the pole to 40° latitude, and therefore will 
exercise a large influence on the development of organic proximate principles. 
Taking into account, then, the wide distribution of Podophyllum peltatum 
throughout the United States, from the New England States to Georgia, i.e. 
between 30° and 45° latitude, and its consequent subjection to various phases of 
climate, and coupling that with the above facts as to temperature, we might 
expect that the plant should flourish in the British Isles. But though it might 
vegetate well and put on a healthy appearance, it does not follow that the con¬ 
stituents of a plant should be found identical in every respect in different 
quarters of the globe, particularly when we remember that in some cases slight 
changes of soil and surrounding circumstances are competent to cause notable 
variations in the formation of active principles. In other instances, however, 
transplantation to another soil under careful management and subject to similar 
conditions of climate, does not militate against the development of medicinal 
properties, and of this the success of the cinchona plantations on the Neilgherry 
Hills, whose yield of alkaloids compares favourably with that derived from the 
Peruvian forests is a conspicuous and familiar example. 
No plant exhibits more strikingly the influence of temperature than hemp. 
In these countries it shoots up luxuriantly aud produces fibre of valuable 
quality, but is almost destitute of its peculiar narcotic resin, having little or no 
odour, aud feeling scarcely adhesive when handled, while under an Indian sun 
it becomes loaded with clammy resin and its fibre is of little value. Again, in 
the case of the gum-bearing acacias, an elevated temperature is essential to the 
production of their viscid exudation, for though the tree may flourish in cooler 
climates, it then yields no gum. 
Examination of the resin extracted from the podophyllum root shows that 
the species is readily acclimatized, and elaborates its characteristic secretion, 
which retains its activity of effect. 
Pdie specimen of the rhizome in the Museum of Materia Medica, Trinity 
College, Dublin, agrees exactly in physical characters with American podo¬ 
phyllum as to thickness, colour, fracture, etc., and it would be almost impossible 
to distinguish between them. 
The method adopted for extracting the resin was as follows :—312 grains of 
the dried, coarsely-powdered drug, was macerated in a small quantity of alcohol, 
* The isothermal lines of the globe for every month of the year are delineated in Professor 
Dove’s work, ‘Die Vorbreitung der Warme,’ for the use of which I am indebted to the Rev. 
Dr. Haughton. 
