Fine structure of the mucocysts of colacium calvum (euglenophyceae)

The characteristic stalk of Colacium calvum Stein is formed from carbohydrate extruded by granules in the anterior portion of the cell. These granules exhibit the characteristics of mucocysts and their contents have two electron densities. A narrow extension of each granule extends past neighboring muciferous bodies to attachment sites in the posterior notch of the pellicle strip. The granule contains neutral polysaccharide which resembles that in the peripheral cisternae of the Golgi apparatus. The attachment site is structurally complex.