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Show 278 DR. F. DAY ON INDIAN FRESHWATER FISHES. [May H, (Bloch), of the respective sizes of 5 fa, 4 fa, and 3^j inches in length, were placed at 6.30 in the glass globe of a hanging lamp measuring 10 inches across and 12 inches deep ; this was filled two-thirds full of fresh water, the temperature being 75° Fahr. A diaphragm ot net was then stretched tightly across the diameter one inch below the water, thus effectually preventing the fish from rising to the surface to obtain atmospheric air. At the end of four minutes they all became excited, and pushed vigorously against the net, which, however, they did not succeed in breaking. They continued at intervals to make these ineffectual efforts, but at 8.1 a.m. the smallest sank down and died, at 8.2 a.m. the medium-sized one, and at 8.8 a.m. the largest. Thus the largest and strongest only lived one hour and twenty-eight minutes when deprived of direct access to atmospheric air. On opening their gills under water and pressing the branchiae no air escaped from the cavity. Experiment No. 2.-To prove satisfactorily that death did not ensue either from deleterious properties in the water or from the exclusion of air by the diaphragm, three more were placed at 8.45 a.m. in the same vessel in which the others had died, the water not having been changed ; it was covered over with the same diaphragm at about an inch above the water. The temperature was then 76°, at 11 a.m. 76°, 12 a.m. 80°, 4 p.m. 78°, 6 p.m. 78°, 10 p.m. 78°; aud, to prevent recapitulation, it may be as well to state that these temperatures, unless otherwise specified, prevailed throughout these experiments. But in this case the fish, being able to reach the air, did well and were taken out the next day, after they had been left in the same water for 24 hours. Experiment No. 3.-Three specimens of Siluroid water-breathers (Macrones tengara) were placed in the same globe similarly prepared as in the first experiment. After 25 hours they were as lively and well as when first put in. It was impossible for them to have obtained atmospheric air direct; but they swam as near the surface as the diaphragm would permit, which may easily be accounted for by the great heat of the water, and the comparatively small amount of fluid contained in the globe. Subsequently this experiment was tried with some Cyprinidse, two specimens of Puntius stigma (Cuv. & Val.), one of Amblypharyngodon jerdoni, all water-breathers, and three Loaches (Platacanthus agrensis). The water-breathers remained unaffected ; but the Loaches died in eight hours. This genus of Loaches have a receptacle for air in the first vertebrae, which circumstance was overlooked when I first described them*. Experiment No. 4.-Three more specimens of Ophiocephalus punctatus were placed in some wet grass in an earthen vessel in which they were kept for upwards of three hours, or double the length of time it took to drown those excluded from atmospheric air and thus compelled to breathe water only. At the end of this time they were all alive and healthy. EapermentTto.5.-Another specimen of the Ophiocephalus nunc talus was held under water, and as much air as possible evacuated * Proc. Zool. Soc. 1865, p. 298. |