I've made the following changes, which are basically working:

• At the end of the last definition, if an item is a single morpheme, a link appears for retrieving all entries containing that morpheme.
• If you click on the link, a list of entries is retrieved, looking exactly like the regular entry list.
• If you click on one of those entries, the content of the entry is retrieved and displayed.

Two problems remain to be solved:

• The content becomes recursive, in that if you click on the tab for the ancestor morpheme inside the parent entry, the ancestor morpheme entry is copied inside itself, including the list of subentries you've already retrieved. They need to be stripped out when copying an entry to a morpheme tab.
• The decision to use a margin-left of -10em when displaying entry lists is causing problems, and needs to be re-thought. It's done in order to achieve a hanging indent, but something subtle will have to be done to override it when processing entry lists retrieved through AJAX and intended for embedding in other lists.