1. There are a number of species where a chloroplast's absence was formerly marked with separate genera such as Astasia (colourless Euglena) and Hyalophacus (colourless Phacus).

2. Eighteen long-established strains of bleached Euglena gracilis (the products of several different bleaching techniques) and two culture-collection stocks of the naturally colorless Astasia longa were examined with electron microscope for the possible presence of plastids.