Answer and Explanation:
The excerpt correctly punctuated is:
It is difficult to determine whose outlook was more bleak. (1)As Lawrence states, Poe had a pretty bitter doom (2) -- he had performed some of the bitterest tasks of human experience. (3)He is reducing his own self as a scientist reduces salt in a crucible. (4)But it is Lawrence himself that speculates: "the human soul must suffer its own isintegration, consciously, if ever it is to survive."
1. A comma is necessary to separate the two clauses.
2. Em dash replaces parenthesis at the end of the sentence.
3. End of sentence needed a peiod/stop.
4. The use of the colon is follwed by the sentence that explains the first sentence.