The ornamental design for an adapter for fluorescenttube, as shown and described.
FIG. 1 is a front elevational view of the adapter for fluorescent tube;
FIG. 2 is a back elevation view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a left side elevation view thereof;
FIG. 7 is a top, front and left side perspective view thereof; and,
FIG. 8 is a top plan view illustrating the adapter connected to an end of a fluorescent tube and held by a contact in a socket.
The broken lines showing the fluorescent tube and socket are included for the purpose of illustrating environmental structures and form no part of the claimed design.