diff --git a/Orange/preprocess/transformation.py b/Orange/preprocess/transformation.py
index 776f3579983..be9ad1d1867 100644
--- a/Orange/preprocess/transformation.py
+++ b/Orange/preprocess/transformation.py
@@ -14,7 +14,6 @@ def __init__(self, variable):
         :type variable: int or str or :obj:`~Orange.data.Variable`
         """
         self.variable = variable
-        self._last_domain = None
 
     def __call__(self, data):
         """
@@ -24,9 +23,17 @@ def __call__(self, data):
         inst = isinstance(data, Instance)
         if inst:
             data = Table(data.domain, [data])
-        domain = Domain([self.variable])
-        data = Table.from_table(domain, data)
-        transformed = self.transform(data.X if sp.issparse(data.X) else data.X.squeeze(axis=1))
+        if self.variable.is_primitive():
+            domain = Domain([self.variable])
+            data = Table.from_table(domain, data)
+            col = data.X
+        else:
+            domain = Domain([], metas=[self.variable])
+            data = Table.from_table(domain, data)
+            col = data.metas
+        if not sp.issparse(col):
+            col = col.squeeze(axis=1)
+        transformed = self.transform(col)
         if inst:
             transformed = transformed[0]
         return transformed
diff --git a/Orange/tests/test_transformation.py b/Orange/tests/test_transformation.py
new file mode 100644
index 00000000000..ae304b4d622
--- /dev/null
+++ b/Orange/tests/test_transformation.py
@@ -0,0 +1,61 @@
+import unittest
+import numpy as np
+
+from Orange.data import Table, Domain, DiscreteVariable, ContinuousVariable, \
+    StringVariable
+from Orange.preprocess.transformation import Identity, Transformation
+
+
+class TestTransformation(unittest.TestCase):
+    class TransformationMock(Transformation):
+        def __init__(self, *args, **kwargs):
+            super().__init__(*args, **kwargs)
+            self.called_with = None
+
+        def transform(self, col):
+            self.called_with = col
+            return np.arange(len(col))
+
+    @classmethod
+    def setUpClass(cls):
+        cls.data = Table("zoo")
+
+    def test_call(self):
+        """Call passes the column to `transform` and returns its results"""
+        data = self.data
+        trans = self.TransformationMock(data.domain[2])
+        np.testing.assert_almost_equal(trans(data), np.arange(len(data)))
+        np.testing.assert_array_equal(trans.called_with, data.X[:, 2])
+
+        np.testing.assert_almost_equal(trans(data[0]), np.array([0]))
+        np.testing.assert_array_equal(trans.called_with, data.X[0, 2])
+
+        trans = self.TransformationMock(data.domain.metas[0])
+        np.testing.assert_almost_equal(trans(data), np.arange(len(data)))
+        np.testing.assert_array_equal(trans.called_with, data.metas.flatten())
+
+        np.testing.assert_almost_equal(trans(data[0]), np.array([0]))
+        np.testing.assert_array_equal(trans.called_with, data.metas[0, 0])
+
+    def test_transform_fails(self):
+        trans = Transformation(self.data.domain[2])
+        self.assertRaises(NotImplementedError, trans, self.data)
+
+    def test_identity(self):
+        domain = Domain([ContinuousVariable("X")],
+                        [DiscreteVariable("C", values=["0", "1", "2"])],
+                        [StringVariable("S")])
+        X = np.random.normal(size=(4, 1))
+        Y = np.random.randint(3, size=(4, 1))
+        M = np.array(["A", "B", "C", "D"], dtype=object).reshape(-1, 1)
+
+        D = Table.from_numpy(domain, X, Y, metas=M)
+        X1 = domain[0].copy(compute_value=Identity(domain[0]))
+        Y1 = domain[1].copy(compute_value=Identity(domain[1]))
+        S1 = domain.metas[0].copy(compute_value=Identity(domain.metas[0]))
+        domain_1 = Domain([X1], [Y1], [S1])
+        D1 = Table.from_table(domain_1, D)
+
+        np.testing.assert_equal(D1.X, D.X)
+        np.testing.assert_equal(D1.Y, D.Y)
+        np.testing.assert_equal(D1.metas, D.metas)