The terrestrial animals, properly so called, are represented by a small species of Diptera with rudimentary wings, podurellæ in large quantities, living with three or four species of small Acarida or mites among mosses and lichens. Upon soft water-wracks there rises a microscopic fauna composed of Nematoidea, Rotifera, Tardigrada, Infusoria, and Rhizopoda. These animals and plants represent at the present day the terrestrial antarctic fauna and flora, and no other living animal has yet been discovered upon the whole extent of the properly called antarctic region, for we cannot consider as terrestrial animals the birds and seals which inhabit this region. The question is to know what has become of the autochtone fauna and flora, which must have inhabited the great antarctic land and wastes during the geological periods, when the ice had not invaded the polar regions. To this question, it seems to me, there is but one answer to be made. The whole terrestrial antarctic fauna was destroyed during the glacial epochs, which, before the present epoch, covered over with ice more completely than to-day the whole antarctic region. We possess decisive information concerning the existence of a vast crystalline cap which stretched over the whole of Patagonia and Tierra del Fuego. Moreover, we observed in Belgica Channel some glacial phenomena which incontestably indicate a much greater extension of ice than the present existing one. I believe that even the plants and terrestrial animals that were found upon the lands of Belgica Strait are not the remains of the antarctic flora and fauna of the preglacial epoch, but American immigrants brought by the large-winged birds which are common to both regions.
Birds are very numerous in the Belgica Channel, and the greater part of them rest in the holes and cracks of the cliffs. With but one exception, the Chionis alba, all are web-footed and are a part of the orders Gavia, Tubinares, Steganopoda, and Impenes. The most common are the Dominican sea-gull (Larus dominicanus), the brown sea-gull (Megalestris antarctica), the sea-swallow (Sterna hirundinacea), the large petrel (Ossifraga gigantea), the bird of tempests (Oceanites oceanicus), the Cape pigeon (Daption capensis), the carunculated cormorant (Phalacrocorax carunculatus), the Papuan penguin (Pygoscelis papua), and the antarctic penguin (Pygoscelis antarctica), these latter two living in vast rookeries; in short, the curious beak-sheathed bird (Chionis alba) which, like most other birds already mentioned, nests in the holes and crevices of rocks.
Two varieties of seals were seen in Belgica Channel—the Weddell seal (Leptonychotes weddelli), frequently met in small bands, and the crab-eater seal (Lobodon carcinophaga), which is more scarce. Among the Cetacea, the Megaptera boöps (?) is met in large troops, often in the company of a large balænoptera (Balænoptera Sibbaldii) (?), but no genuine black or Greenland bone whale was ever seen. The littoral fauna and flora are badly represented on account of the constant motion of the ice along the rocky shores of the sea. Sea-wracks cannot fix themselves upon them, nor can animals. Yet in some well-sheltered crevices I found some rare sea-grasses (Desmarestia, etc.), and patellæ with small inferior animals.
The first biological example we could ascertain, during our imprisonment of thirteen months in the ice-pack, was a general presence of diatomaceæ on the superficial sheets of the sea, as well as upon icebergs and in the interior of the holes and cracks of the sea-ice. The most frequently represented species are Chætoceros, Coscinodiscus, and Chorethron. The bed or plant is not very rich and but little varied. It is composed of small-sized animals, of which the most frequently represented are enumerated in the order of their frequency: the Copepodaes Radiolaria (Protocystis, Cannosphæra), Pteropoda (Limacina), Polychæta (Pelagobia), Copelata (Oikopleura), Ostracoda, Siphonophora (Eudoxia), etc.
The size of the bed or plant undergoes a season’s change. During the winter, sea-ice, being very thick, intercepts daylight; in consequence the diatomaceæ cannot increase and the bed decreases considerably in size. In the summer, on the contrary, sea-ice thins, cracks, and tracks are numerous; light can thus penetrate, which accounts for an abundant growth of diatomaceæ, and the bed increases considerably in volume.
One of the most important plancton forms or plants, with regard to the part it plays in the economy of antarctic life, is a species of the Euphausia kind. In fact, there exist immense shoals of this animal under the ice-pack, and these shoals serve as an almost exclusive food for seals, penguins, and presumably cetaceans.
Dredgings performed upon the continental plateau spoken of elsewhere brought forth a fauna which, from its general character, shows a remarkable affinity with the abyssal fauna. We fished, in effect, pedunculated Crinoidea, Elasipoda, benthal Asterias, Aselidæ, Pantopoda, Gorgonidæ, Polychæta, Cumacea, Mysidæ, Ascidiæ, which have a striking air of relationship with the similar forms fished in the great oceanic depths. This fact ought not to astonish us, for we well know that the great factor in the distribution of marine animals is temperature. Now, the temperature of the water upon this plateau of five hundred metres in depth is much the same as that of the oceanic depths. The groups best represented are the Echinodermata, Crustacea (Edriophthalma), Polychæta, Gorgonidæ, and Bryozoa. The birds which were constantly present upon the ice-pack are not numerous: the very large petrel (Ossifraga gigantea), the snow petrel (Pagodroma nivea), the antarctic petrel (Thalassocca antarctica), the brown sea-gull (Megalestris antarctica), Forster’s penguin (Aptenodytes forsteri), and the Adelia land penguin (Pygosulis adeliæ).
The whole four seal species inhabiting the antarctic were seen during our stay in the ice-pack; that is, the crab-eater seal (Lobodon carcinophaga), Weddell sea-leopard (Leptonychotes weddelli), the true sea-leopard (Ogmorhynus leptonyx), and Ross’s seal (Ommatophoca Rossi). Balænoptera of a small size and Ziphiidæ came very often to breathe in the cracks and leads of the ice-pack. The temperature of the bodies of the seals is about +37°, that of the penguins about +40°. These figures are below the normal. These animals, in order to fight against the exterior cold, do not create more heat than this, only they lose less, and they arrive at this result by means of the thick covering of fat which surrounds them. Direct observations allow us to state this fact. The cold does not appear to have a pernicious influence upon the human organism. In temperatures of from -30° to -40° and calm weather, the feeling one experiences is rather pleasant and invigorating. It is naturally otherwise when the wind blows. I believe that for a traveller the great inconvenience of cold upon the ice-pack is that it creates a condensation of aqueous vapour which is eliminated by the skin’s surface. At the end of a short time the clothes are all wet, and it is hard under such conditions to get warm. But the greatest inconvenience in polar regions lies in the absence of the sun during the winter months. The pernicious influence of the absence of direct sunbeams, upon the human organism, was witnessed to a certainty during the winter of 1898.
The whole crew of the Belgica, without exception, presented symptoms which in medical books are grouped under the name of chronic anæmia. With them all we could notice a discoloration of the mucous membranes, dyspnœa, acceleration of the pulse, dizziness, insomnia, a complete incapacity for prolonged intellectual work, and even a swelling of the legs. The report of the surgeon of the expedition promises to be interesting under this head.
I have spoken only to call attention to the studies which were made by the members of the expedition in Patagonia and Tierra del Fuego. They will bring out some zoological, botanical, geological, and anthropological contributions for the knowledge of these important regions of the globe.