The ornamental design for a vessel for a respirometer, as shown and described.
FIG. 1 is a perspective view of a vessel for use in a respirometer of the present design showing the top, front, and first side portions of the vessel;
FIG. 2 a perspective view of a vessel for use in a respirometer of the present design showing the top, back, and second side portions of the vessel;
FIG. 3 is a perspective view of a vessel for use in a respirometer of the present design showing the bottom, back, and second side portions of the vessel;
FIG. 4 is a top view of a vessel for use in a respirometer of the present design showing the top portion of the vessel;
FIG. 5 is a back view of a vessel for use in a respirometer of the present design showing the back portion of the vessel;
FIG. 6 is a bottom view of a vessel for use in a respirometer of the present design showing the bottom portion of the vessel; and,
FIG. 7 is a side view of a vessel for use in a respirometer of the present design showing the second side portion of the vessel.
In the drawings, the broken lines are for the purpose of illustrating environment only and form no part of the claimed design.