diff --git a/mathicsnotebook/kernel.py b/mathicsnotebook/kernel.py
index 35f4026..3a5e53c 100755
--- a/mathicsnotebook/kernel.py
+++ b/mathicsnotebook/kernel.py
@@ -19,6 +19,18 @@ class MathicsNotebookKernel(Kernel):
 
     name = 'MathicsNotebook'
 
+
+    """
+    Initialize Mathics core.
+    """
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+
+        self.definitions = Definitions(add_builtin=True)
+        self.evaluation  = Evaluation(self.definitions, format='xml')
+
+
+
     """
     Preprocess output for better support for graphics.
     """
@@ -26,29 +38,26 @@ def preprocess_output(self, data):
         data = re.sub(r"<math><mglyph width=\"(.*)\" height=\"(.*)\" src=\"(.*)\"/></math>", "<img width=\"\\1\" height=\"\\2\" src=\"\\3\" />", data, 0)
 
         return data
-    
+
     """
     Handle jupyter connections.
     """
     def do_execute(self, code, silent, store_history=True,
                    user_expressions=None, allow_stdin=False):
-        
+
         if not silent:
             from mathics.core.parser import MultiLineFeeder
 
-            definitions = Definitions(add_builtin=True)
-            evaluation  = Evaluation(definitions, format='xml')
-
             feeder = MultiLineFeeder(code, '<notebook>')
             results = []
             try:
                 while not feeder.empty():
-                    expr = evaluation.parse_feeder(feeder)
+                    expr = self.evaluation.parse_feeder(feeder)
                     if expr is None:
-                        results.append(Result(evaluation.out, None, None)) 
-                        evaluation.out = []
+                        results.append(Result(self.evaluation.out, None, None))
+                        self.evaluation.out = []
                         continue
-                    result = evaluation.evaluate(expr, timeout=20)
+                    result = self.evaluation.evaluate(expr, timeout=20)
                     if result is not None:
                         results.append(result)
             except Exception as exc:
@@ -56,14 +65,14 @@ def do_execute(self, code, silent, store_history=True,
 
             for result in results:
                 result_data = result.get_data()
-                
+
                 result_html = self.preprocess_output(result_data['result'])
-                
+
                 display_data = {
                     'data' : {'text/html' : result_html},
                     'metadata' : {},
                 }
-                
+
                 self.send_response(self.iopub_socket, 'display_data', display_data)
 
         return {
@@ -74,9 +83,7 @@ def do_execute(self, code, silent, store_history=True,
         }
 
     def do_complete(self, code, cursor_pos):
-        definitions = Definitions(add_builtin=True)
-
-        matches_raw = definitions.get_matching_names(code + '*')
+        matches_raw = self.definitions.get_matching_names(code + '*')
         matches     = []
 
         for match in matches_raw: