diff -r b7727edd44f2 -r 10f3b3286e63 lemon/circulation.h
--- a/lemon/circulation.h	Wed Nov 28 17:51:02 2007 +0000
+++ b/lemon/circulation.h	Wed Nov 28 18:01:38 2007 +0000
@@ -231,6 +231,12 @@
 
     /// @}
 
+  protected:
+
+    Circulation() {}
+  
+  public:
+
     /// The constructor of the class.
 
     /// The constructor of the class.