244 NATURAL SCIENCE. APRIL, 
No doubt scientific men are very sensitive to any remarks on 
their ignorance; but we feel impelled to make these comparisons for 
their own sakes. It should clearly be recognised that the study of the 
habits of marine animals and of the interdependence of the various 
species in any fauna, needs something beyond museum work. 
Properly to understand the natural history of the deep-sea we must 
adopt a different method of procedure; we must examine the 
creatures alive, and under natural conditions. This has no doubt 
partially been done with a few of the species that will live in aquaria; 
but most marine animals have never been studied in the living state 
and cannot thrive in confinement. 
SUBMARINE PHOTOGRAPHY. 
THERE seems, however, to be an unused method of research, 
which ought to yield satisfactory results, and should help us to under- 
stand what sort of life is led by the inhabitants of the deep-sea. 
Photography could, we believe, be used for submarine exploration 
without much difficulty, and we are surprised that so little has yet 
been done. Our ordinary photographic lenses would, of course, be 
useless for this purpose; but lenses to act through a denser medium 
could easily be made. In the second place, the pressure at consider- 
able depths is so great that a camera of the usual pattern would not 
do; we must have the camera full of water, and with no air-spaces 
anywhere. This brings us to the last, and probably most serious, 
difficulty. How can the sensitive plates be preserved from injury if 
they are immersed in water? It could be done by laying another 
glass plate on the film, and photographing through glass, though this 
would tend somewhat to blur the image. A better way would be, if 
possible, to waterproof the sensitive film, and dissolve away the 
varnish before developing the plate. 
By some such mode of procedure it is probable that we could 
obtain photographs as far down as light penetrates. We might even 
use the electric spark to illuminate the surroundings at great depths ; 
for a hollow sealed sphere of thick glass will stand an enormous 
pressure. For the study of the manners and customs of the deep-sea 
fishes, a few sub-aqueous photographs would be invaluable. Coral- 
reefs also, though so carefully studied and well photographed down 
to low-water mark, are not understood. A series of photographs of 
the steep, submerged portion of the reef ought to throw a great deal 
of light on the vexed question of the origin of coral islands. We hope 
that some enterprising amateur photographer will take up this 
question, and begin by photographing in their native haunts the 
inhabitants of some of our lakes or sheltered sea-lochs. 
FRUIT-GROWING AT THE CAPE. 
Fruit-GrowIinc at the Cape is in an unsatisfactory way, accord- 
ing to Professor Macowan’s account in the January number of the 
