Einar didn't go to Madame Jasmin-Carton's for the same reason as the other men. […] He only wanted to watch the girls strip and dance, to study the curve and heft of their breasts, to watch the thighs, eerily white and tremulous like the skin on a bowl of steamed milk, flap open and closed. (13.9)
We'll stop there before it gets too steamy, but here we see Einar going to a strip club not to be titillated, but to study, as an artist would study a landscape. In order to be a woman, Einar wants to know how to act like one.
She would let out a little gasp when she discovered that down there, between her white, goose-pimpled thighs, lay a certain shriveled thing. It was so vile to her that she would snap closed her thighs, tucking it away, her knee bones smacking. (13.16)
In Paris, Einar becomes more and more disgusted with his male body parts, and the word choice by the author—"shriveled," "goose-pimpled," "smacking"—is intended to make Einar's penis seem as repulsive as possible.