diff --git a/Framework/Cascade/Cascade.h b/Framework/Cascade/Cascade.h
index 2d5088ed343530c945f9f16fbd124440088063e3..f47266e9e5012c35849dfa13f34c82071a0bebf6 100644
--- a/Framework/Cascade/Cascade.h
+++ b/Framework/Cascade/Cascade.h
@@ -230,14 +230,15 @@ namespace corsika::cascade {
 
         auto const assertion = [&] {
           auto const* numericalNodeAfterStep =
-              fEnvironment.GetUniverse()->GetContainingNode(particle.GetPosition());
+              fEnvironment.GetUniverse()->GetContainingNode(particle.GetPosition()); 
           return numericalNodeAfterStep == currentLogicalNode;
         };
 
         assert(assertion()); // numerical and logical nodes don't match
-      } else {               // boundary crossing
+      } else {               // boundary crossing, step is limited by volume boundary
         std::cout << "boundary crossing! next node = " << nextVol << std::endl;
         particle.SetNode(nextVol);
+	// DoBoundary may delete the particle (or not)
         fProcessSequence.DoBoundaryCrossing(particle, *currentLogicalNode, *nextVol);
       }
     }
diff --git a/Framework/StackInterface/Stack.h b/Framework/StackInterface/Stack.h
index 9d259e1c282b278ab9bcec4f37a337685e29d641..8deb9d5107196bef57b5d47766c1cc38e3e7abbc 100644
--- a/Framework/StackInterface/Stack.h
+++ b/Framework/StackInterface/Stack.h
@@ -33,8 +33,8 @@ namespace corsika::stack {
      <b>Important:</b> ParticleInterface must inherit from ParticleBase !
    */
 
-  template <typename>      //, bool>
-  class ParticleInterface; // forward decl
+  template <typename>      
+  class ParticleInterface; 
 
   /**
      The Stack class provides (and connects) the main particle data storage machinery.
@@ -98,8 +98,8 @@ namespace corsika::stack {
     typedef StackDataType
         StackImpl; ///< this is the type of the user-provided data structure
 
-    template <typename SI>                //, bool IsBase>
-    using PIType = ParticleInterface<SI>; //, IsBase>;
+    template <typename SI>                
+    using PIType = ParticleInterface<SI>; 
 
     /**
      * Via the StackIteratorInterface and ConstStackIteratorInterface
@@ -209,7 +209,6 @@ namespace corsika::stack {
       }
       if (p.GetIndex() < GetSize() - 1) fData.Copy(GetSize() - 1, p.GetIndex());
       DeleteLast();
-      // p.SetInvalid();
     }
     /**
      * delete this particle