A lot of people studied with Bouguereau at the Julian. I am not sure Parkhurst is a reliable source as his own work is weak and far from Bouguereau's. Bouguereau did a standard ebauche not unlike Gérôme or Cabanel: a light ground beginning with a colored frottis. The technique was David's in a sense, passed to Bouguereau from Picot. However, it's the subsequent veils of color that refine the modeling and contribute to the mottled effect of his skin. Occasionally he would paint a vein or two beneath the skin and veil over it, thus mimicking flesh in the way you explained. His debt to Boucher was the Rococo complexion, greenish halftones with pink cheeks, toes and fingers (and an occasional belly button).