Passing derived class members to base class constructer?

I'm trying to derive a class from HtmlTextWriter to specifically write Html to a string.
This means constructing the HtmlTextWriter class with some strings, but as these strings are part of the derived class, I can't pass them to the base class constuctor! Here's my code. Any ideas to get around this?
Of course I can simply have an instance of HtmlTextWriter within the base class, but then I can't just call all the members of HtmlTextWriter directly in my HtmlStringWriter class. :(

Code:

---

public class HtmlStringWriter : HtmlTextWriter
{
    StringBuilder htmlString;
    StringWriter stringWriter;
    //
    public HtmlStringWriter()
    {
        htmlString = new StringBuilder(); // this will hold the string
        stringWriter = new StringWriter(htmlString);
        base(stringWriter);
    }
}

---