But fellow internationals Courtney Lawes, Lee Dickson and Ben Foden return to the starting line-up for the Franklin’s Gardens clash (kick-off 3.15pm).
Hartley sustained a lung injury in England’s 30-22 defeat to New Zealand last Saturday and was forced to go to hospital after the game.
Wood also picked up a knock at Twickenham, meaning both remain unavailable for Saints duty.
Also missing are Alex Corbisiero (knee), James Craig (shoulder), George Pisi (suspended) and five men on international duty.
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Kahn Fotuali’i and Ken Pisi are in action for Samoa this weekend, George North for Wales, Samu Manoa for the USA and Vasily Artemyev for Russia.
Boss Jim Mallinder has still been able to ring the changes, though, with 11 alterations to the starting line-up which smashed London Irish 39-18 in the LV= Cup last weekend.
Jamie Elliott and Sam Dickinson have shrugged off injuries to start at 14 and eight respectively, while Luther Burrell, Stephen Myler, Alex Waller, Mike Haywood and Phil Dowson return after being rested for the match at the Madejski Stadium.
Dowson captains the team from six, while Calum Clark, a replacement last weekend, comes in at seven.
James Wilson, Tom Collins, Salesi Ma’afu and Christian Day are the only starting survivors from the Irish success.
Saints: Foden; Elliott, Wilson, Burrell, Collins; Myler, Dickson; A Waller, Haywood, Ma’afu, Lawes, Day, Clark, Dowson (c), Dickinson.
Replacements: McMillan, E Waller, Mercey, van Velze, Nutley, A Day, G Dickson, Waldouck.
Newcastle Falcons: Tait; Cato, Barnes, Powell, Shortland; Godman Blair; Vickers, Lawson, Tomaszczyk, del Fava, McKenzie, Mayhew, Welch, Hogg.
Replacements: McGuigan, Shiells, Wilson, MacLeod, York, Fury, Clegg, Fitzpatrick