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Show 1868.] DR. F. DAY ON INDIAN FRESHWATER FISHES. 279 from the receptacle by pressing upon the superior branchiae. Most of the air was discharged, and the specimen was placed, like the others, under the diaphragm. But death did not ensue; it remained in a sluggish state for seven hours at the bottom of the globe, not even attempting to rise and obtain air. At the end of this time another fish was placed in the same globe without having had the air removed from the receptacle, whilst the first specimen, without being allowed to rise to the surface, had the gills opened, and the whole of the air (if there was any) remaining in the cavity abstracted by means of a syringe with a long pipe. The new arrival appeared to arouse the previously dormant fish into activity, and they both dashed wildly about, but died within two hours. The exertion no doubt caused excitement of the circulation, necessitating a larger supply of air. On opening their gills under water no air escaped, thereby proving that it is not generated beneath the water. Experiment No. 6.-A bandage was stitched pretty tightly around the head of another specimen of the same species at 8 a.m., so as to entirely prevent its opening its gills, care having been taken not to obstruct its eyesight. It was then placed in a globe of water; but this process did not appear to inconvenience it in any way, and after submitting to it for 24 hours, it was as lively as possible. In this case it was impossible that the gills could have been opened; the fish, therefore, must have sustained life by aerial respiration. Experiment No. 7.-The same fish, without the bandage having been removed, was, after the lapse of this time, viz. 24 hours, placed in water beneath a diaphragm, in company with another which had been in the same vessel with it all the previous day. In the space of half an hour the bandaged fish died from being unable to pass water through its gills. After death the cavity contained no air. The other specimen lived for 17 hours in a sluggish state, rarely moving at the bottom of the globe, showing, as in experiment No. 5, that these fish can live in a quiescent state for some time in water although aerial respiration is precluded, and that they must therefore be able to take in a certain amount of air from the water by means of their branchiae, although not in sufficient quantity to support life for more than a limited period. Experiment No. 8.-A bandage was stitched round the head of a Macrones tengara, a water-breather, in the same manner as in the last experiment. It died in 34 minutes; but in this instance the gill-opening could not be entirely closed, owing to the serrated pectoral spine being beneath it. Experiment No. 9.-A specimen of Ophiocephalus punctatus was placed in a dry cloth at 9.55 a.m., and left without any moisture, the temperature being at 76° Fahr. It lived until 1.20 p.m., occasionally opening its mouth and taking in air. At 12.15 it was able to move across the table, whence it fell on to the ground, and was only picked up after it had proceeded several feet across the room. This fall in its dry state may have injured it and hastened its death. At all events it lived entirely without moisture for three hours and twenty-five minutes ; and it is doubtful whether it did not |