(661) HABERT, E.W. & W.H. BECKERT, 1971. Sex distinguishing chromatin in some invertebrates. Cytologia 36 (1): 190-197. – (Dept. Biol., St. John’s Univ., Jamaica, N. Y. II432, USA). Representatives of Mollusca, Annelida and Arthropoda were investigated to determine the presence or absence of sex specific chromatin masses. The Feulgen technique and 2 different techniques using Biebrich scarlet and fast green FCF were used to demonstrate sex distinctive chromatin in tissue sections. No nuclear dimorphism was noted in Myriapoda and in 9 out of 11 insect orders examined. Thus in Odon. the nuclei of flight muscle, gut, epithelial and connective tissue cells of Libellula pulchella, Anax junius and Lestes uncatus had no sex distinctive masses.