. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RESISTANCE OF FISHES. 327 water had filled all the bottles and had been running through them for some time, during which time the corks of all the bottles had been sealed with modeling clay, it was again tested for concentration and constancy of dissolved gas. The samples were usually collected at the exit tube of bottle C. If the tests showed the desired concentration to be present and constant, fishes were quickly introduced, the corks rapidly replaced and reseated, and observations begun. Because of the fact that at. FIG.