History of Science and Onions

First I have to apologise about the quality of this shot. This piece sold about 45 minutes after I finished it, so I didn't really have time to get a good record of it.
There are about 5 different pieces under the final work, and most of them show through in some area or other. I made no attempt at obliterating the previous works, but just worked straight over them.
Conté on canvas