In Memoriam: Richard Dean Allen.

It is remarkable, that apart from his printed legacy, Richard left behind also a pictorial legacy by creating in 2006 the extraordinary website " I Paramecium i and Other Ciliates: Richard Allen's Image Collection" (https://www..pbrc.hawaii.edu/allen/). Thereby, some parts of the membrane are rescued by partial retrieval (as discoidal vesicles) from the discharging food vacuole and used for the formation of a new food vacuole at the cytostome (Allen & Fok, [6]; Fok & Allen, [12], [13]). Aside from that, he was repeatedly invited to contribute articles for review organs, for example, I International Review of Cytology i (Allen & Fok, [6]; Allen & Naitoh, [8]; Fok & Allen, [12]), I Cell Biology International i (Tani et al., [21]), and chapters for monographs, for example, I Membrane Fusion i (Allen, [2]), I Paramecium i (Allen, [3]), I Advances in Cell and Molecular Biology of Membranes i (Allen & Fok, [5]; Fok & Allen, [13]), I Osmotic and Ionic Regulation: Cells and Animals i (Allen et al., [10]) and I Methods in Cell Biology i (Hausmann & Allen, [18]). Richard Dean Allen passed away on February 10, 2023, in Honolulu, Oahu, Hawaii, the United States. [Extracted from the article]