diff --git a/session_4/session_4.Rmd b/session_4/session_4.Rmd
index c5cb263ddf9e8da0fe2daf071c8672290784ab1c..173f3f338f1edfdb866446aadfe12a4906acef02 100644
--- a/session_4/session_4.Rmd
+++ b/session_4/session_4.Rmd
@@ -502,6 +502,7 @@ ggplot(expr_DM1, aes(samples, Genes, fill= log1p(counts))) +
     axis.text.x = element_text(size = 4, angle = 90)
   )
 ```
+**Nota bene :** The elements of the axes, and the theme in general, are modified in the `theme()` function. 
   </p>
 </details>
 
@@ -532,3 +533,5 @@ ggplot(expr_DM1, aes(samples, Genes, fill= log1p(counts))) +
 
 
 
+
+