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 (juestion 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-Growing at the Cape is in an unsatisfactory way, accord- 

 ing to Professor Macowan's account in the January number of the 



