Alice and the Caterpillar

This is another in a series that depends heavily on erotic things. In this one there's the puppy scene petty much as it is in the regular book. Alice then walks around, finds a giant mushroom and gets on the top only to find the Caterpillar.

She needs to get directions the the Mad Hatter's Tea Party so she asks him. Turns out he's equpped to give sex in two of the three openings and one of these is not the mouth. Why was this series done?