The Geographical Journal (Journal of the Royal Geographical Society): Volume XII, No. 2 [‎271v] (45/154)

136 THE ANNUAL RANGE OF TEMPERATURE IN THE SURFACE WATERS OI THE
would collect. Then other people would have an opportunity of knowing something,
and possibly of challenging Dr. Murray’s opinions in consequence of the acquisition
of fresh data. _ -r, ht
Mr. George Murray : I can amply confirm the conclusion that Dr. Murray
has arrived at with regard to bipolarity of organisms so far as they are concerned
with the flora, both the littoral flora (those organisms that we call seaweeds) and
also those that live far away from land. There is no doubt this bipolarity is
especially striking in these organisms that live far away from land. Quite recently,
however, with the help of Miss Barton, I made a minute examination of all the
known littoral seaweeds in the arctic and antarctic regions, and we found a very
high percentage of species in common; but this, however, is nothing to the com
munity of type that exists among those minute organisms that live in the ocean.
For example, the polar regions north and south are inhabited characteristically in
the open ocean by diatoms, the temperate seas by Peridinieai and coccospheres, and
the tropics by Peridinieas, coccospheres, rhabdospheres, and other forms. Now, I had
my conclusions (which were very likely somewhat cut and dry) a little upset last
summer. You know the diatoms are characteristic of the polar sea, and find their
finest development there, but yet they are always more abundant near land than
they are in the open ocean ; in fact, by the use of a tow-net and a microscope, you
would know almost as well as with a Thomson sounder when you are coming near
land by the increase of the diatoms you get in your tow-net. I found in a traverse
of the Atlantic that I made last summer, and from observations made for me for a
whole year between the Channel and the Caribbean sea by officers of the Royal Mail
Steam Packet Company—I found from those observations that there were very few
diatoms as soon as we got away from land, but when we got close to Barbados we
got more, and rather more again in the Caribbean sea, and when we got to Panama
we got an extraordinary number. The diatoms are abundant in Colon bay from
August to February, from the two extremes of temperature (there is very little
range of temperature there—from 81° to 83°), and I venture to say they are quite
as abundant there as they are in the arctic regions, or as they are in Loch Fyne,
which, I believe, holds the record for diatoms in the number to the cubic inch,
if I may put it that way. I should like to get an explanation from Dr. Murray ;
I should like to know whether temperature alone has much to do with this. It is
quite true that in a place like Colon bay we have a very stable temperature,
just as in the arctic and antarctic we have a very stable temperature. I
must say the species we found in Colon bay were inseparable from the species we
found in Loch Fyne. I should like to know whether the chemical constitution of
the water has not something to do with this. One is rather apt to suspect this
from the fact that diatoms are so abundant near land. I should like to know if
these other factors have not something to do with this question of distribution, I
mean besides temperature. I do not yield even to Dr. Mill in my estimate of
the value of the facts brought before us by Dr. Murray; but I do plead for other
factors besides temperature being taken into consideration, especially in dealing
with such highly complex things as living organisms.
Dr. Gregory : I am glad of the opportunity as a biologist of expressing gratitude
to Dr. Murray for this brilliantly original and suggestive paper, for it is on the
researches of physicists that the biologists must rely for the explanation of the
riddles of biological distribution. There are many points in the paper, I think,
that will help biologists to explain some of those difficulties. During the last few
years there has been a strong tendency to attribute all deposition of carbonate of
lime from the sea to the direct action of life, but Dr. Murray’s experiment of the
precipitation of carbonate of lime from sea-water by the addition of ammonium