ma."

The paradoxical character of this general observation lies in the fact
that a low temperature retards development, and hence should be
expected to have the opposite effect from that mentioned by Chun. Recent
investigations have led to the result that life-phenomena are affected
by temperature in the same sense as the velocity of chemical reactions.
In the case of the latter van't Hoff had shown that a decrease in
temperature by 10 degrees reduces their velocity to one half or less,
and the same has been found for the influence of temperature on the
velocity of physiological processes. Thus Snyder and T.B. Robertson
found that the rate of heartbeat in the tortoise and in Daphnia is
reduced to about one-half if the temperature is lowered 10 deg C., and
Maxwell, Keith Lucas, and Snyder found the same influence of temperature
for the rate with which an impulse travels in the nerve. Peter observed
that the rate of development in a sea-urchin's egg is reduced to less
than one-half if the temperature (within certain limits) is reduced by
10 degrees. The same effect of temperature upon the rate of development
holds for the egg of the frog, as Cohen and Peter calculated from
the experiments of O. Hertwig. The writer found the same
temperature-coefficient for the rate of maturation of the egg of a
mollusc (Lottia).

All these facts prove that the velocity of development of animal life
in Arctic regions, where the temperature is near the freezing point of
water, must be from two to three times smaller than in regions where the
temperature of the ocean is about 10 deg C. and from four to nine times
smaller than in seas the temperature of which is about 20 deg C. It is,
therefore, exactly the reverse of what we should expect when authors
state that the density of organisms at or near the surface of the ocean
in polar regions is greater than in more temperate regions.

The writer believes that this paradox finds its explanation in
experiments which he has recently made on the influence of temperature
on the duration of life of cold-blooded marine animals. The experiments
were made on the fertilised and unfertilised eggs of the sea-urchin, and
yielded the result that for the lowering of temperature by 1 deg C.
the duration of life was about doubled. Lowering the temperature by 10
degrees therefore prolongs the life of the organism 2 to the power 10,
i.e. over a thousand times, and a lowering by 20 degrees prolongs it
about on