diff --git a/Assets/Prefabs/Heart.prefab b/Assets/Prefabs/Heart.prefab
index a4a1e5e..d06b333 100644
Binary files a/Assets/Prefabs/Heart.prefab and b/Assets/Prefabs/Heart.prefab differ
diff --git a/Assets/Scripts/Health.cs b/Assets/Scripts/Health.cs
index c3e1654..7a239fc 100644
--- a/Assets/Scripts/Health.cs
+++ b/Assets/Scripts/Health.cs
@@ -11,42 +11,62 @@ public class Health : MonoBehaviour
 
 	private ArrayList hearts = new ArrayList();
 
+	// Width (X) and height (Y) of an heart image with additional blank space
 	private float spaceX;
 	private float spaceY;
 
 	void Start () 
 	{
-		RectTransform r = heartImage.rectTransform;
-		spaceX = r.rect.width;
-		spaceY = r.rect.height;
-		Debug.Log("spaceX : " + spaceX);
-		Debug.Log("spaceY : " + spaceY);
+		spaceX = 2.3f;
+		spaceY = 2.3f;
+
 		AddHearts (startingHealth);
 	}
 
-	void AddHearts (int n) 
+	public void AddHearts (int n) 
 	{
 		for (int i = 0; i < n; i++) 
 		{
 			Transform heart = ((Image)Instantiate(heartImage)).transform;
-			heart.SetParent(GameObject.Find("HeartCanvas").transform, false);
 
+			// Add heart image to the canvas
+			heart.SetParent(GameObject.Find("Canvas").transform, false);
+
+			// Calculate x and y position of the new heart (in number of hearts)
 			int y = Mathf.FloorToInt(hearts.Count/maxHeartsPerRow);
 			int x = hearts.Count - y * maxHeartsPerRow;
 
-			Debug.Log("X : " + x);
-			Debug.Log("Y : " + y);
-
 			Vector2 pos = heart.position;
 			pos.x += x * spaceX;
-			pos.y += y * spaceY;
-
-			Debug.Log("posX : " + pos.x);
-			Debug.Log("posY : " + pos.y);
+			pos.y += -y * spaceY;
 
 			heart.position = pos;
 
+			// Add heart
 			hearts.Add(heart);
 		}
 	}
+
+	public void LoseHearts(int n)
+	{
+		for (int i = 0; i < n && i < hearts.Count; i++) 
+		{
+			int lastIndex = hearts.Count - 1;
+
+			// Destroy the image of the last heart
+			Image heartImage = (Image)((Transform)hearts[lastIndex]).GetComponent("Image");
+			Destroy(heartImage);
+
+			// Remove the last heart
+			hearts.RemoveAt(lastIndex);
+		}
+	}
+
+	void OnCollisionEnter2D(Collision2D collision) 
+	{ 
+		if( collision.gameObject.tag == "Ennemy" )
+		{
+			LoseHearts(1);
+		}
+	}
 }
diff --git a/Assets/Scripts/Health.cs.meta b/Assets/Scripts/Health.cs.meta
index 558e382..5d53882 100644
--- a/Assets/Scripts/Health.cs.meta
+++ b/Assets/Scripts/Health.cs.meta
@@ -1,10 +1,11 @@
 fileFormatVersion: 2
 guid: 496d8c4c25eff1443b8789ad17b173c5
-timeCreated: 1447945584
+timeCreated: 1447986069
 licenseType: Free
 MonoImporter:
   serializedVersion: 2
-  defaultReferences: []
+  defaultReferences:
+  - heartImage: {fileID: 11427978, guid: 5c6327fc8da56da4e8a5949457d56e76, type: 2}
   executionOrder: 0
   icon: {instanceID: 0}
   userData: