Try this for the macro:
Code:
Sub CopySelectedCells()
For Each cll In Selection.Cells
Range("C15").Value = Range("C15").Value & " " & cll.Value
Next cll
End Sub
It will only copy text, no formatting such as bold colour etc.
Note also that it will copy the cells in the order you selected them in, even if the cells are next to each other. For example you could hold the Ctrl key down then in sequence click on C10, then C9 then C8, you'll get:
Only formulas and number formatting. The width of one column or range of columns to another column or range of columns. Cell contents and formatting except cell borders.
It's not quite perfect, it adds a space for the first cell copied too.