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Show 320 MR. G. E. DOBSON ON T H E [May 19, surface, and consequently was soonest asphyxiated when retained under water*. The faculty of living out of water, or when the gills are kept in a moistened condition only, not only for hours, but in some cases for days, possessed by many species of Symbranchida, Labyrinthici, and Ophiocephalida especially, is not alone a wonderful provision of nature enabling these animals to resist the prolonged droughts of the countries they are found in, but is also of the greatest importance to the inhabitants of these countries, who are well acquainted with their vitality out of water, and take advantage of it in transporting them long distances, and in being able to maintain their supply fresh till required for use. Accordingly these fish, though not very delicate in flavour, are highly esteemed by the people of Bengal, especially by the poorer classes, and great quantities of Anabas scandens, Trichogaster fasciatus, Ophiocephalus punctatus, O. striatus, and Amphi-pnous cuchia are daily exposed for sale in the bazars. The Anabas, which has the greatest vitality of all out of water except the Amphipnous, is kept in closely woven baskets, about one hundred individuals or more in each basket. Thus lying close together, evaporation is greatly lessened and their gills are kept moist. In this condition they live, I have been told by many native fishermen, for four or five days. In very dry weather some water is daily thrown on them, or the basket is immersed for a short time in water. A constant supply of fresh fish is thus afforded, the importance of which can only be fully appreciated in tropical countries, where fish taken in the morning are often unfit for use by breakfast time. The experiments here recorded were but the commencement of what I had intended to be a series, including every Indian freshwater fish possible to procure alive. They were undertaken at the suggestion of Mr. Francis Day, to whose most interesting paper on this subject I have referred above. M y investigations were suddenly interrupted by m y unexpected return to Europe; and as 1 now see no prospect of revisiting the East Indies for some years, I think it may be well to record the few observations made. The following Table (p. 321) exhibits the results of the experiments above described, and also of Mr. Day's investigations. The species of fish are arranged according to the time required to produce asphyxia when deprived of access to the surface of the water. The position of Amphipnous cuchia is uncertain. * As remarked by Mr. Day (loc. cit. p. 279), some fishes which take in air at the surface of the water (compound breathers), possess the power of remaining in a state of semitorpidity at the bottom, and in this condition exist for many hours without respiring. This will account for the difference of time required to produce asphyxia in individuals of the same species noted in foregoing observations. |
