A mesostic is a poem or other text arranged so that a vertical phrase intersects lines of horizontal text. It is similar to an acrostic, but with the vertical phrase intersecting somewhere in the midst of the line, as opposed to the beginning of each line.
The practice of using index words to select pieces from a preexisting text was developed by Jackson Mac Low as "diastics". It was used extensively by the experimental composer John Cage (Walsh 2001).
There are two types of mesostic: fifty percent and one hundred percent. (See also the example below.)
Below, an example of a one-hundred-percent mesostic:
KITCHEN let us maKe of thIs modesT plaCe a room Holding tons of lovE (&, Naturally, much good food, too)
It qualifies as a one-hundred-percent mesostic because there is no k or i in the text between the capital K of line 1 and the capital I of line 2 – let us maKe of thIs– no i or t between the capital I and T – of thIs modesT– and so on.