The problem of cytology and cytochemistry of cannibal giant cells is of interest to cellular biologists. Cannibalism is not unusual among the Protozoa. Studies have been made on cannibal giants of Stentor coeruleus by various investigators (Johnson, 1893; Gelei, '25; Ivanic, '27 and Tartar, '61. This phenomenon has been also reported in the Genus Blepharisma. Dawson ('29) was the first to describe cannibal giantism in these ciliates. Giese ('38) later noted that cannibalistic tendency could be produced in Blepharisma americanum at will. Tulchin and Hirshfield ('62) studied the fate of DNA and RNA of the ingested animal in food vacuole of B. americanum.
The authors attention was drawn towards the study of Blepharisma, not because of its cannibalistic tendency per se but because of the fact that cannibalism is associated with giantism in this genus. This phenomenon does not occur in the ciliate genera: Stentor and Frontonia.
Previously, it has been assumed that the nuclear dimorphism in ciliates indicated a functional difference. The genetic function being performed by the micronucleus and the metabolic by the macronucleus. Recent works on ciliates cast some doubt on this concept. It provided evidence to show that the macronucleus can perform both functions. This evidence is based not only on the natural occurrence of amicronucleate races and species of ciliates (Beers, '46) but also on the many regeneration experiments (Balamuth, '40; Tartar, '61). The potentialities of these amicronucleate forms as shown by laboratory studies, have conclusively demonstrated that the micronucleus is not necessary for the maintenance of the essential processes of the individual whereas the macronucleus is indispensable. In addi-,