function watch(address _tokenAddr) 
        ownerExists(msg.sender) 
    {
        uint oldBal = tokenBalances[_tokenAddr];
        uint newBal = ERC20(_tokenAddr).balanceOf(this);
        if (newBal > oldBal) {
            _deposited(0x0, newBal-oldBal, _tokenAddr, new bytes(0));
        }
    }