What are those cartoon segments in Monty Python's Flying Circus supposed to parody?

What are those cartoon segments in Monty Python’s Flying Circus supposed to parody? I notice they have a certain look to them–is there any deeper meaning besides just absurdism?

Is there some kind of 19th century cartoon style they are ridiculing? It isn’t clear.

Terry Gilliam liked the look of old illustrations. Absurdism is sufficient explanation for anything Pythonian.

They’re just Terry Gilliam’s peculiar personal style of animation.

He actually did take some elements from old pictures. That image of God from Monty Python and the Holy Grail is some old Cricket Player, or something. The Foot that stomps down on everything at the beginning of each show is from a painting (Cupid and Psyche, or something).

Cupid’s foot reversed

Mostly the cartons are original to Monty Python, and if you see it now it’s copying their style.

That would be W.G. Grace. The only reason I know is that I was reading the Wiki Holy Grail entry just the other day, and it is mentioned specifically, complete with link.

Terry Gilliam is working in collage. There are many precursors for this, including Max Ernst’s Une Semaine de Bonté: