markably interesting examples of
the growth of ice crystals on the walls of the cave and has observed
the same unaccountable confusion of the size of grains in the ice,
showing how little history can be gathered from the structure of ice.

This evening Nelson gave us his second biological lecture, starting
with a brief reference to the scientific classification of the
organism into Kingdom, Phylum, Group, Class, Order, Genus, Species;
he stated the justification of a biologist in such an expedition,
as being 'To determine the condition under which organic substances
exist in the sea.'

He proceeded to draw divisions between the bottom organisms without
power of motion, benthon, the nekton motile life in mid-water, and
the plankton or floating life. Then he led very prettily on to the
importance of the tiny vegetable organisms as the basis of all life.

In the killer whale may be found a seal, in the seal a fish, in
the fish a smaller fish, in the smaller fish a copepod, and in the
copepod a diatom. If this be regular feeding throughout, the diatom
or vegetable is essentially the base of all.

Light is the essential of vegetable growth or metabolism, and light
quickly vanishes in depth of water, so that all ocean life must
ultimately depend on the phyto-plankton. To discover the conditions
of this life is therefore to go to the root of matters.

At this point came an interlude--descriptive of the various biological
implements in use in the ship and on shore. The otter trawl, the
Agassiz trawl, the 'D' net, and the ordinary dredger.

A word or two on the using of 'D' nets and then explanation of
sieves for classifying the bottom, its nature causing variation in
the organisms living on it.

From this he took us amongst the tow-nets with their beautiful
silk fabrics, meshes running 180 to the inch and materials costing 2
guineas the yard--to the German tow-nets for quantitative measurements,
the object of the latter and its doubtful accuracy, young fish trawls.

From this to the chemical composition of sea water, the total salt
about 3.5 per cent, but variable: the proportions of the various salts
do not appear to differ, thus the chlorine test detects the salinity
quantitatively. Physically plankton life must depend on this salinity
and also on temperature, pressure, light, and movement.

(If plankton only inhabits surface waters, then density, temperatures,
&c., of surface waters must be the important factors. W