Intestinal ciliates and their endosymbionts from the cockroach hindgut: evolutionary aspects AHAM Van Hoek, TA Van Alen, VSI Sprakel, JHP Hackstein and GD Vogels Reprod. Nutr. Dev., 37 Suppl. 1 (1997) 72 DOI: 10.1051/rnd:19970755