the mind gets morbid

Captain Delano in Melville's Benito Cereno - November 1855:

Well, well; these long calms have a morbid effect on the mind, I've often heard, though I never believed it before.

Captain of U.S. Dragoons in Scenes Beyond the Western Border, Southern Literary Messenger, March 1853 pages 157-8:

It may result from our profession, that the mind has these fits of morbid activity, as if to revenge itself for seasons of neglect.

Note:  this 1853 comment on "morbid activity" of "the mind" was deleted in revision of "Scenes Beyond the Western Border" and does not appear in the 1857 book version, Scenes and Adventures in the Army.  Why cut it...too close to the phrasing of practically the same idea in "Benito Cereno," first published October-November-December 1855 in Putnam's?