DOMESTICATED AND ACCLIMATISED FISHES; ARTIFICIAL IMPREGNATION OF OVA--TENACITY OF LIFE AND REPRODUCTION OF LOST PARTS--HYBERNATION--USEFUL AND POISONOUS FISHES. A few fishes only are thoroughly domesticated--that is, bred in captivity, and capable of transportation within certain climatic limits--viz. the Carp, Crucian Carp (European and Chinese varieties), Tench, Orfe or Ide, and the Goramy. The two former have accompanied civilised man almost to every place of the globe where he has effected a permanent settlement. Attempts to acclimatise particularly useful species in countries in which they were not indigenous have been made from time to time, but were permanently successful in a few instances only; the failures being due partly to the choice of a species which did not yield the profitable return expected, partly to the utter disregard of the difference of the climatic and other physical conditions between the original and new homes of the fish. The first successful attempts of acclimatisation were made with domestic species, viz. the Carp and Gold-fish, which were transferred from Eastern Asia to Europe. Then, in the first third of the present century, the Javanese Goramy was acclimatised in Mauritius and Guiana, but no care seems to have been taken to insure permanent advantages from the successful execution of the experiment. In these cases fully developed individuals were transported to the country in which they were to be acclimatised. The most successful attempt of recent years is the acclimatisation of the Trout and Sea-Trout, and probably also of the Salmon, in Tasmania and New Zealand, and of the Californian Salmon (_Salmo quinnat_?), in Victoria, by means of artificially-impregnated ova. The ova were transported on ice, in order to retard their development generally, and thus to preserve them from destruction during the passage of the tropical zone. _Artificial impregnation_ of fish-ova was first practised by J. L. JACOBI, a native of Westphalia, in the years 1757–63, who employed exactly the same method which is followed now; and there is no doubt that this able observer of nature conceived and carried out his idea with the distinct object of advantageously restocking water-courses which had become unproductive, and increasing production by fecundating and preserving all ova, of which a great proportion, in the ordinary course of propagation, would be left unfecundated or accidentally perish. Physiology soon turned to account Jacobi’s discovery, and artificial impregnation has proved to be one of the greatest helps to the student of embryology.