This brass tube was found inside the surgeon’s wooden chest and was for some time believed to be some kind of piston whistle, similar to a modern swanee whistle or bird warbler, which were used to teach songbirds to sing.
However, the design makes this difficult as when your mouth is placed on the end it overlaps the window on the top, preventing it from sounding. In any case, why would a surgeon keep one of these in his chest?
More recent examination and comparison with other similar items showed that it wasn’t a whistle at all. It appears that it is actually a clyster, an enema pipe which would have had a pig’s bladder mounted on the flanged end, allowing fluid to be administered rectally.