Cell reference based on active cell

   Dim rngData As Range

   Set rngData = Intersect(ActiveCell.Offset(, 2).EntireColumn, ActiveSheet.Range("37:49"))

    With ActiveChart
        .ChartType = xlXYScatterLines
        With .SeriesCollection.NewSeries
            .XValues = rngData
            .Values = rngData.Offset(, 1)
        End With
    End With