"Analysis of the Sexual Impulse," in vol. iii of these Studies.
"The accomplishment of no other function," Hyrtl remarks, "is so intimately connected with the mind and yet so independent of it."
The process is still, however, but imperfectly understood; see Art. "Fécondation," by Ed. Retterer, in Richet's Dictionnaire de Physiologie, vol. vi, 1905.