Heat ½ pt. of the fish stock and in it soak the breadcrumbs. Melt ½ oz. butter in a deep pan and in it toss the shrimps over gentle heat for 5 min. Add lemon juice, nutmeg, breadcrumbs and ½ pt. stock, heat gently for 5 min., beat in the rest of the butter. Pound this paste and rub it through a wire sieve. Gradually add the wine and the rest of the fish stock and bring to boiling-point. Mix the egg yolk with the milk or cream. Season the soup carefully, remove it from the heat, stir in the egg and cream mixture and cook this without allowing the soup to boil.