\documentclass{ppex}
\nonstopmode
\usepackage {mfpic,ifthen}
\pagestyle{empty}
\setlength\textwidth{207.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage {mfpic,ifthen}
\begin{mfpic}[1.5]{-40}{50}{-48}{50}
\newcounter{mfcntA}
\newcounter{mfcntB}
\setcounter{mfcntA}{50}
\setcounter{mfcntB}{48}
\whiledo{\themfcntA>1}{%
  \expandafter\curve{(\themfcntA,0),
    (0,\themfcntA),
    (-\themfcntA,0),
    (0,-\themfcntB),
    (\themfcntB,0)}
   \addtocounter{mfcntA}{-2}%
   \addtocounter{mfcntB}{-2}%
 }
\end{mfpic}
\end{document}