Portsmouth loan for Marcus.
The midfielder will join up with Andy Awford's squad until January 3rd and is expected to go straight into the squad for Pompey's home game against Morecambe on Saturday.
After being injured during pre-season, Marcus returned to full fitness but his chances in the first team have been limited due to the form of Alex Gilbey, George Moncur and more recently David Fox.
He was made available for loan by boss Tony Humes, who feels that it is best for Marcus to get out and play some games.
He said: "This is a great chance for Marcus to go out and kick start his career again, it has stagnated a bit here in the past couple of months.
"He is a fantastic professional and his attitude has been spot on around the training ground, despite him not being involved in the first team."