11. Each stanza of "Hanging Fire" ends with a period, but there are no commas or other punctuation elsewhere. What is the effect of the lack of punctuation?

Unclear question, however I inferred you are referring to the poem "Hanging Fire".

Answer:

Gives the reader opportunity to absorb reached each thought.

Explanation:

In the poem it gives the reader an brief moment to absorb or reflect on thought expressed in each stanza.

Since there are no commas or other punctuation elsewhere, the reader would have to, or is expected to read through at a fast pace until the end of each stanza where he/she then reflects.