582 Linnean Society. 
to the evidence which his own life afforded of the peaceable disposi- 
tion, the unquestionable loyalty, the intelligence and high moral worth 
which belong to that large portion of the people of England. 
« In the death of Mr. Drummond we have to lament the loss of 
a very useful man ; one to whom we have been indebted for many 
years for many rare plants which he collected in the Rocky Moun- 
tains during his first expedition to North America, and in the 
valley of the Mississippi in his last visit to that continent. He was 
sent out principally through the} instrumentality of Sir William J. 
Hooker, for the purpose of making collections in all the depart- 
ments of natural history ; and thereare some present who know how 
well he accomplished the objects of his mission. His plants were 
purchased by several naturalists in this country, in France, and 
America; and I understand from Sir W. Hooker that indepen- 
dent of the sums he had successively paid towards the expenses of 
Mr. D.in America, and towards the support of his family in Scotland, 
there is a considerable balance due to his widow. Mr. Drummond 
died of fever last year at the Havannah; and I feel that his death 
is scarcely less disastrous than that of Mr. Douglas. 
« It does not seem to be sufficiently known that the natives of the 
colder regions inevitably run great hazard of sickness and death 
in resorting to climes of a high mean temperature. When it is 
recollected what a remarkable exemption from mortality has uni- 
formly characterized the arctic expeditions under Sir J. Ross, 
Sir E. Parry, Sir J. Franklin, and Captain Back, and what a 
frightful destruction of life followed the naval and military expe- 
ditions to the West Indies in the war of 1793, and how many ex- 
cellent men have successively perished in the fatal attempt to ex- 
plore Africa, it is an irresistible conclusion that a high mean tem- 
perature is most prejudicial to the health of those unaccustomed 
to its influence: and the fact, I believe, is satisfactorily explained 
by the more prolific sources of disease which may reasonably 
be supposed to exist in the teeming climes of the south, and the 
effect which a sudden change of temperature exerts on the hu- 
man body. When we reflect, for instance, that in this country the 
mean temperature is about 52°, and that we consequently have a 
vital energy equivalent to the production of 46° of animal heat to 
enable us to maintain the blood at its standard heat of 96°; and 
that a native of Great Britain, by resorting to a clime where the 
mean temperature is 75° or 80°, cannot accommodate himself at 
once to this great change of circumstances,—that is, with a power to 
generate 46°, he cannot at once lose this power, and generate only 
21° or 16°, to put himself on a level with the condition of the native 
of a tropical clime,—it will be evident that if he falls under the influ- 
ence of the causes of fever, the disease must have in him a violenceand 
a precipitancy highly dangerousto life. I believe this fully explains 
the nature and fatality of what is called yellow fever ; a disease en- 
tirely unknown té the natives of the West Indies and the most south- 
ern states of North America. Dr. Ramsey of Charleston, South Ca- 
rolina, shows for a long series of years that the deaths by yellow fever 
in that city have been confined exclusively to strangers, and that no 
