diff --git a/Cantera/python/Cantera/Transport.py b/Cantera/python/Cantera/Transport.py
index 6d5edbdb6..92c232301 100755
--- a/Cantera/python/Cantera/Transport.py
+++ b/Cantera/python/Cantera/Transport.py
@@ -1,10 +1,9 @@
 """ Cantera provides a set of classes for 'transport managers' that
 manage the computation of various transport properties of a phase of
-matter. Every object
-representing a phase of matter for which transport properties are needed
-has a transport manager assigned to
-it. The transport manager has only one job: to compute the values
-of the transport properties of its assigned phase.
+matter. Every object representing a phase of matter for which
+transport properties are needed has a transport manager assigned to
+it. The transport manager has only one job: to compute the values of
+the transport properties of its assigned phase.
 
 A transport manager may do additional things not apparent to the user
 in order to improve the speed of transport property evaluation. For
@@ -26,6 +25,15 @@ class Transport:
     """Transport property manager.
     A transport property manager is responsible for computing transport
     properties.
+
+    In the C++ kernel, a transport manager implements a single
+    transport model, and is an instance of a subclass of the base
+    class 'Transport'.  The structure in Python is a little
+    different. A single class 'Transport' represents any kernel-level
+    transport manager. In addition, multiple kernel-kevel transport
+    managers may be associated with one Python transport manager,
+    allowing the model used to compute transport properties to be
+    switched at any time.
     """
     def __init__(self, xml_phase=None,
                  phase=None, model = "", loglevel=0):
@@ -54,6 +62,7 @@ class Transport:
         self._models[self.model] = self.__tr_id
 
     def __del__(self):
+        """Delete all installed transport models."""
         if hasattr(self,'_models'):
             for m in self._models.keys():
                 try:
@@ -62,12 +71,14 @@ class Transport:
                     pass
 
     def addTransportModel(self, model, loglevel=1):
+        """Add a new transport model to this transport manager."""
         new_id = _cantera.Transport(model,
                                     self._phase_id, loglevel)
         self._models[model] = new_id
         
 
     def switchTransportModel(self, model):
+        """Switch to a different transport model."""
         if self._models.has_key(model):
             self.__tr_id = self._models[model]
         else:
@@ -92,25 +103,33 @@ class Transport:
         return _cantera.tran_viscosity(self.__tr_id)
 
     def thermalConductivity(self):
+        """Thermal conductivity. [W/m/K]."""
         return _cantera.tran_thermalConductivity(self.__tr_id)
 
     def thermalDiffCoeffs(self):
+        """Return a one-dimensional array of the species thermal diffusion
+        coefficients. Not implemented in all transport models."""
         return _cantera.tran_thermalDiffCoeffs(self.__tr_id,
                                              self.trnsp)
 
     def binaryDiffCoeffs(self):
+        """Two-dimensional array of species binary diffusion coefficients."""
         return _cantera.tran_binaryDiffCoeffs(self.__tr_id,
                                              self.trnsp)
 
     def mixDiffCoeffs(self):
+        """Mixture-averaged diffusion coefficients."""
         return _cantera.tran_mixDiffCoeffs(self.__tr_id,
                                          self.trnsp)            
 
     def multiDiffCoeffs(self):
+        """Two-dimensional array of species multicomponent diffusion
+        coefficients."""
         return _cantera.tran_multiDiffCoeffs(self.__tr_id,
                                            self.trnsp)
 
     def setParameters(self, type, k, params):
+        """Set model-specific parameters."""
         return _cantera.tran_setParameters(self.__tr_id,
                                            type, k, asarray(params))
     
diff --git a/Cantera/src/EdgeKinetics.cpp b/Cantera/src/EdgeKinetics.cpp
index c893b1132..28ca9beae 100644
--- a/Cantera/src/EdgeKinetics.cpp
+++ b/Cantera/src/EdgeKinetics.cpp
@@ -16,7 +16,7 @@
 #include "SurfPhase.h"
 
 #include "ReactionData.h"
-#include "StoichManager.h"
+//#include "StoichManager.h"
 #include "RateCoeffMgr.h"
 
 #include <iostream>
diff --git a/Cantera/src/InterfaceKinetics.cpp b/Cantera/src/InterfaceKinetics.cpp
index 211cb9440..2633f93f3 100644
--- a/Cantera/src/InterfaceKinetics.cpp
+++ b/Cantera/src/InterfaceKinetics.cpp
@@ -16,7 +16,7 @@
 #include "SurfPhase.h"
 
 #include "ReactionData.h"
-#include "StoichManager.h"
+//#include "StoichManager.h"
 #include "RateCoeffMgr.h"
 
 #include "ImplicitSurfChem.h"
diff --git a/Cantera/src/ReactionStoichMgr.cpp b/Cantera/src/ReactionStoichMgr.cpp
index 40c81f580..c558ce10f 100644
--- a/Cantera/src/ReactionStoichMgr.cpp
+++ b/Cantera/src/ReactionStoichMgr.cpp
@@ -92,7 +92,7 @@ namespace Cantera {
             vector_fp delta_order(nr,0.0);
             for (n = 0; n < nr; n++) {
                 delta_order[n] = r.order[n] - r.rstoich[n];
-                cout << "rxn stoich " << r.reactants[n] << "   " << r.order[n] << "  " << delta_order[n] << endl;
+                //cout << "rxn stoich " << r.reactants[n] << "   " << r.order[n] << "  " << delta_order[n] << endl;
             }
             m_global->add(rxn, r.reactants, delta_order);
         }
diff --git a/Cantera/src/StoichManager.h b/Cantera/src/StoichManager.h
index 440215e4c..3d12368a6 100755
--- a/Cantera/src/StoichManager.h
+++ b/Cantera/src/StoichManager.h
@@ -98,6 +98,12 @@ namespace Cantera {
    * 
    */
 
+    static doublereal ppow(doublereal x, doublereal order) {
+        if (x > 0.0)     
+            return pow(x, order);
+        else 
+            return 0.0;
+    }
 
   /**
    * Handles one species in a reaction.
@@ -121,7 +127,7 @@ namespace Cantera {
       *(output + m_rxn) *= *(input + m_ic0); 
     }
     void power(const doublereal* input, doublereal* output) const { 
-      output[m_rxn] *= pow(input[m_ic0], m_order); 
+      output[m_rxn] *= ppow(input[m_ic0], m_order); 
     }
     void incrementSpecies(const doublereal* input, 
 			  doublereal* output) const { 
@@ -169,8 +175,8 @@ namespace Cantera {
     }
 
     void power(const doublereal* input, doublereal* output) const { 
-      output[m_rxn] *= pow(input[m_ic0],m_order0) * 
-	pow(input[m_ic1],m_order1); 
+      output[m_rxn] *= ppow(input[m_ic0],m_order0) * 
+	ppow(input[m_ic1],m_order1); 
     }
 
     void incrementSpecies(const doublereal* input, 
@@ -238,9 +244,9 @@ namespace Cantera {
 	* (*(input + m_ic2)); 
     }
     void power(const doublereal* input, doublereal* output) const { 
-      output[m_rxn] *= pow(input[m_ic0],m_order0) * 
-	pow(input[m_ic1],m_order1) * 
-	pow(input[m_ic2],m_order2);
+      output[m_rxn] *= ppow(input[m_ic0],m_order0) * 
+	ppow(input[m_ic1],m_order1) * 
+	ppow(input[m_ic2],m_order2);
     }
     void incrementSpecies(const doublereal* input, 
 			  doublereal* output) const {
@@ -300,7 +306,7 @@ namespace Cantera {
 
     void power(const doublereal* input, doublereal* output) const {
       for (int n = 0; n < m_n; n++) output[m_rxn] 
-	*= pow(input[m_ic[n]],m_order[n]); 
+	*= ppow(input[m_ic[n]],m_order[n]); 
     }
 
     void multiply(const doublereal* input, doublereal* output) const {
diff --git a/Makefile.in b/Makefile.in
index 72b427e97..05e2161c4 100755
--- a/Makefile.in
+++ b/Makefile.in
@@ -260,9 +260,9 @@ docs:
 depends:
 	cd Cantera; @MAKE@ depends
 	cd tools; @MAKE@ depends
-	ifeq ($(build_particles	,1)
+ifeq ($(build_particles),1)
 		cd Cantera/cads; @MAKE@ depends
-	endif
+endif
 
 changes: 
 	cvs2cl.pl --prune
diff --git a/tools/testtools/Makefile.in b/tools/testtools/Makefile.in
index befb59cc8..046fe2983 100644
--- a/tools/testtools/Makefile.in
+++ b/tools/testtools/Makefile.in
@@ -36,6 +36,9 @@ depends: $(DEPENDS)
 	cat *.d &> .depends
 	$(RM) $(DEPENDS)
 
+TAGS: 
+	etags *.h *.cpp
+
 ifeq ($(wildcard .depends), .depends)
 include .depends
 endif