Middle English Verse Punctuation: A Sample Survey.
The limited tradition of mid-verse punctuation in non-alliterative ME poetry is not all connected to the tradition of separating alliterative half-lines with a point, but instead probably began as a means of separating verses written in prose lineation. It gained popularity as a way of separating short lines written in a long-line format, then appeared in a syntactic and metrical role in the Vernon, Ellesmere, and Hengwrt MSS. The Vernon MS. features a mid-line point with line-by-line regularity in the majority of its four-stress non-alliterative verses, but has less regular mid-verse punctuation in texts of other meters.
Text 4 (1988): 163-88.
Killough, George B.