diff --git a/source/Layer.cpp b/source/Layer.cpp
index 54a268c..6e87c2e 100644
--- a/source/Layer.cpp
+++ b/source/Layer.cpp
@@ -16,8 +16,8 @@ using namespace std;
 
 Layer::Layer(const string &name, size_t id, size_t numVisibleX, size_t numVisibleY, size_t numHidden)
 : Rbm(numVisibleX*numVisibleY, numHidden)
-, upper(nullptr)	
-, lower(nullptr)	
+, next(nullptr)	
+, prev(nullptr)	
 , m_name(name)
 , m_id(id)
 , m_numVisibleX(numVisibleX)
@@ -29,8 +29,8 @@ Layer::Layer(const string &name, size_t id, size_t numVisibleX, size_t numVisibl
 
 Layer::Layer(const Layer& orig)
 : Rbm(orig.bv().n_elem, orig.bh().n_elem)
-, upper(nullptr)	
-, lower(nullptr)	
+, next(nullptr)	
+, prev(nullptr)	
 , m_name(orig.m_name)
 , m_weightsFile(orig.m_weightsFile)
 , m_id(orig.m_id)
@@ -166,9 +166,9 @@ Json::Value Layer::toJson() const
 arma::mat Layer::up_pass(const arma::mat &hidden)
 {
 	arma::mat reconstruction = toVisibleProbs(hidden);
-	if (upper)
+	if (next)
 	{
-		return upper->up_pass(reconstruction);
+		return next->up_pass(reconstruction);
 	}
 	return toHiddenProbs(reconstruction);
 }
@@ -176,9 +176,9 @@ arma::mat Layer::up_pass(const arma::mat &hidden)
 arma::mat Layer::down_pass(const arma::mat &visible)
 {
 	arma::mat hidden = toHiddenProbs(visible);
-	if (lower)
+	if (prev)
 	{
-		return lower->down_pass(hidden);
+		return prev->down_pass(hidden);
 	}
 	return toVisibleProbs(hidden);
 }
diff --git a/source/Layer.hpp b/source/Layer.hpp
index 33adf6f..30e7b0f 100644
--- a/source/Layer.hpp
+++ b/source/Layer.hpp
@@ -24,10 +24,10 @@
 class Layer : public Rbm
 {
 public:
-	Layer *upper;
-	Layer *lower;
+	Layer *next;
+	Layer *prev;
 
-	Layer(const std::string &prjname, size_t id, size_t numVisibleX, size_t numVisibleY, size_t numHidden);
+	Layer(const std::string &name, size_t id, size_t numVisibleX, size_t numVisibleY, size_t numHidden);
 	Layer(const Layer& orig);
 	virtual ~Layer();
 
diff --git a/source/Stack.cpp b/source/Stack.cpp
index 5c4928f..45a2e51 100644
--- a/source/Stack.cpp
+++ b/source/Stack.cpp
@@ -10,7 +10,7 @@
  * 
  * Created on 25. Oktober 2019, 18:26
  */
-
+#include <cassert>
 #include "Stack.hpp"
 
 using namespace std;
@@ -37,7 +37,7 @@ size_t Stack::numLayers()
 	while(pLayer)
 	{
 		count++;
-		pLayer = pLayer->upper;
+		pLayer = pLayer->next;
 	}
 	return count;
 }
@@ -47,17 +47,17 @@ void Stack::addLayer(Layer *pOtherLayer)
 	if (!m_pLayers)
 	{
 		m_pLayers = pOtherLayer;
-		pOtherLayer->lower = nullptr;
+		pOtherLayer->prev = nullptr;
 	}
 	else
 	{
 		Layer *pLayer = m_pLayers;
-		while(pLayer->upper) 
+		while(pLayer->next) 
 		{
-			pLayer = pLayer->upper;
+			pLayer = pLayer->next;
 		}
-		pLayer->upper = pOtherLayer;
-		pOtherLayer->lower = pLayer;
+		pLayer->next = pOtherLayer;
+		pOtherLayer->prev = pLayer;
 	}
 }
 
@@ -70,13 +70,13 @@ Layer* Stack::getLayer(size_t layerId) const
 		{
 			return pLayer;
 		}
-		pLayer = pLayer->upper;
+		pLayer = pLayer->next;
 	}
 	return nullptr;
 	
 }
 
-bool Stack::load()
+bool Stack::load(LayerConstructor *pLayerConstructor)
 {
 	std::cout << "Importing Project " << m_name << std::endl;
 	ifstream ifs(m_name + string(".prj"));
@@ -85,7 +85,7 @@ bool Stack::load()
 	Json::Value project;
 	reader.parse(ifs, project);
 	
-	const string &prjname = project["stack"]["name"].asString();
+	const string &name = project["stack"]["name"].asString();
 	Json::Value &layers = project["stack"]["layers"];
 			
 	for (int i=0; i < layers.size(); i++)
@@ -96,7 +96,19 @@ bool Stack::load()
 		int numVisibleX = layer["numVisibleX"].asInt();
 		int numVisibleY = layer["numVisibleY"].asInt();
 		int numHidden = layer["numHidden"].asInt();
-		Layer *pLayer = new Layer(layername, i, numVisibleX, numVisibleY, numHidden);
+		
+		Layer *pLayer = nullptr;
+		if (!pLayerConstructor)
+		{
+			pLayer = new Layer(layername, i, numVisibleX, numVisibleY, numHidden);
+		}
+		else
+		{
+			pLayer = pLayerConstructor->onConstruct(layername, i, numVisibleX, numVisibleY, numHidden);
+		}
+		
+		assert(pLayer != nullptr);
+		
 		pLayer->fromJson(layer["rbm"]);
 		addLayer(pLayer);
 	}
@@ -118,7 +130,7 @@ bool Stack::save()
 	while(pLayer)
 	{
 		layers.append(pLayer->toJson());
-		pLayer = pLayer->upper;
+		pLayer = pLayer->next;
 	}
 	project["stack"]["layers"] = layers;
 	
@@ -133,7 +145,7 @@ void Stack::weightsInit(double stddev)
 	while(pLayer)
 	{
 		pLayer->weightsInit(stddev);
-		pLayer = pLayer->upper;
+		pLayer = pLayer->next;
 	}
 }
 
@@ -146,7 +158,7 @@ bool Stack::loadWeights()
 		{
 			return false;
 		}
-		pLayer = pLayer->upper;
+		pLayer = pLayer->next;
 	}
 	return true;
 }
@@ -160,7 +172,7 @@ bool Stack::saveWeights()
 		{
 			return false;
 		}
-		pLayer = pLayer->upper;
+		pLayer = pLayer->next;
 	}
 	return true;
 }
@@ -171,7 +183,7 @@ void Stack::train(const arma::mat& batch, Rbm::IListener* pListener)
 	while(pLayer)
 	{
 		train(pLayer->id(), batch, pListener);
-		pLayer = pLayer->upper;
+		pLayer = pLayer->next;
 	}
 }
 
@@ -186,7 +198,7 @@ void Stack::train(size_t layerId, const arma::mat& batch, Rbm::IListener* pListe
 			break;
 		}
 		thisBatch = pLayer->toHiddenProbs(thisBatch);
-		pLayer = pLayer->upper;
+		pLayer = pLayer->next;
 	}
 	
 	if (pLayer)
diff --git a/source/Stack.hpp b/source/Stack.hpp
index 4bf5159..01cb660 100644
--- a/source/Stack.hpp
+++ b/source/Stack.hpp
@@ -20,6 +20,18 @@
 #include <jsoncpp/json/json.h>
 #include "Layer.hpp"
 
+class LayerConstructor
+{
+public:
+	LayerConstructor() {}
+	virtual ~LayerConstructor() {}
+	
+	virtual Layer* onConstruct(const std::string &name, size_t id, size_t numVisibleX, size_t numVisibleY, size_t numHidden)
+	{
+		return nullptr;
+	}
+};
+
 class Stack
 {
 public:
@@ -32,7 +44,7 @@ public:
 
 	void train(size_t layerId, const arma::mat& batch, Rbm::IListener* pListener);
 	void train(const arma::mat& batch, Rbm::IListener* pListener);
-	bool load();
+	bool load(LayerConstructor *pLayerConstructor=nullptr);
 	bool save();
 	void weightsInit(double stddev);
 	bool loadWeights();