This is from The Prahran Telegraph (Sat 23 July 1898):-In Round 10 of 1898, Fitzroy v. St. Kilda, match reports (The Age, The Argus, The Australasian) state that St. Kilda played with only 18 players against the 20 of Fitzroy due to selected players failing to appear, however 20 players are credited with playing.
The 9 mentioned in match reports are:
Aylwin, Harry
Blake, Mick
Blake, Tom
Dando, Johnny
Hall, Ted
Jones, Ernie
Matthews, Bill
Smith, Howard
Stewart, Andy
The 11 credited as playing but not mentioned are:
Fogarty, Tom
Gibson, Dave
Hogan, Joe
McNamara, Tom
Morehouse, Joe
Phillips, Syd
Stewart, George
Stewart, Walter
Warne, Jim
Whitelaw, Fred
Woodhouse, Bill
Presumably two of this list did not actually play - but clues as to the non-attendees are scant. (I've also looked at Leader, Herald, Fitzroy City Press, Table Talk) As A. Stewart is mentioned with an initial this suggests there were likely to be multiple Stewarts on the field. Neither Fogarty or Gibson played the next week but this may be purely coincidental.
This time they had an additional reason to plead for the defeat in that only 18 men took the field at the start of the game.
The Saints put their full 20 into the field in the last portion of the game, and the presence of the extra men had a marked difference on the game.
http://trove.nla.gov.au/newspaper/article/144638898
I've certainly not seen it mentioned in any of the other papers that they eventually did have a full team of 20 players.