The odd couple of protistology: Edward Heron-Allen (1861-1943) and Arthur Earland (1866-1958).

Edward Heron-Allen and Arthur Earland were among the last great amateur foraminifera researchers. Their partnership began in 1907 and ended in 1932. While close in age to one another, they shared little more than a fascination for forams and a lack of any university training. In most other aspects, the two men were completely different. Heron-Allen was a famous upper class polymath, expert not only on forams, but also on the Persian language, violins, palm reading, history, asparagus, and barnacles. He was also an accomplished novelist and poet, who frequented literary circles. In contrast to the flamboyant Heron-Allen, Earland was a discrete civil servant who admitted to working on forams as a relief from the monotony of his job. Hence, the two were improbable partners. However, together they produced 39 substantial works on forams. Their studies concerned assemblages from Southern Ocean to the North Sea and they are today credited with the original description of 186 species. Here the distinct lives of the two men are presented, and their contributions to protistology, as partners as well as individuals, are reviewed. The case is made for considering Earland's work as neglected relative to that of Heron-Allen, except perhaps by foram taxonomists.

Phaeogromids of the mesopelagic marine plankton: Temporal variability of concentrations and observations of feeding structures of four species from the mesopelagic in the Mediterranean Sea.

Challengerids, phaeogromids rhizarian protists, are emblematic protists of the deep sea but are also enigmatic as they occur in very low concentrations. In previous studies, we reported on temporal changes in abundance at a near-shore mesopelagic site, but only as part of sampling of the entire microplankton assemblage, not well-suited for examining phaeogromids. Consequently, we turned to using a closing plankton net to provide material from large volumes of seawater, thus allowing for more robust estimates of concentrations and material for observations of living cells, to our knowledge the first made. Here, we report our results on the four most commonly occurring species: Challengeranium diadon, Challengereron willemoesii, Challengeria xiphodon, and Euphysetta lucani. In contrast to our previous report, we found that changes in concentrations were not related to water column stratification, and the four species roughly co-varied with time. Observations of live cells revealed that all four species deploy tentacle-like pseudopods and also very large unstructured webs of fine pseudopods. The similarities in feeding webs suggest similar prey are exploited, and the similar temporal changes in abundances suggest a common factor or factors (unknown at this time) govern their concentrations. Films of live cells are provided in Supplementary Files.

The saga of the false fossil foram Eozoon.

Eozoon canadense, 'the dawn animal of Canada', a large foraminifera, was announced in 1864 as the oldest fossil organism known. Camps soon formed into disbelievers of its fossil nature, agnostics, and "Eozoonists". Eozoon would number among its proponents major figures of the time. The saga of Eozoon, or more precisely the dispute as to its actual nature, spawned hundreds of publications. Here the story is told with a new focus, one on the stature and roles of the major personalities involved, and the evidence they presented. Eozoon is considered to have been 'de-bunked' in the late 19th century. However, it will be shown that it was never indisputably proven to be inorganic. Rather Eozoon simply faded away after its most ardent defenders died. As late as 1947, it was shown as the primordial organism in a biology textbook. The saga of Eozoon remains as a valuable cautionary tale. It is an example of an artifact accepted as fact because it filled a troubling void in knowledge, i.e., at that time, the first traces of life before Cambrian, and it endured because it was promoted by only a few, but powerful, figures in the scientific establishment of the era.

Jacob Whitman Bailey (1811-1857): Ehrenberg's ambassador to America.

Science in general, and microscopy in particular, lagged far behind Europe in early 19th century America. Jacob Bailey was one of the very few American microscopists. In eulogies he was called 'the Ehrenberg of America' and 'the founder of microscopical research'. He was a major figure in the scientific community of America in his time and instrumental in promoting microscopy and the study of microscopic organisms. His name maybe familiar to specialists who focus on diatoms, foraminifera, or radiolaria. However, Bailey's important contributions to protistology have received very little attention and he is rarely mentioned in histories of protistology. Here Jacob Bailey's life, his protistological works, as well as his roles in the development of microscopy in America and the 19th century debate over life in the deep sea, are reviewed.

Re-visiting the ridiculed rival of Leeuwenhoek: Louis Joblot (1645-1723).

Louis Joblot published one of the first manuals of microscopy in 1718, just a few years before both he and Leeuwenhoek died. It contained Joblot's microscope designs and his extensive observations on microorganisms including experiments on spontaneous generation. Joblot's work and his observations have often been overlooked, misdated, and denigrated. This is due to attention given to a few apparently fanciful drawings of microorganisms, and the identification of his work as appearing in a posthumous 1754 edition. The second edition not only placed Joblot's work as decades after Leeuwenhoek's death, but was also expanded by the publisher to include unattributed material from famous sources. Here an attempt is made to shine a light on Joblot's work and bring it out of Leeuwenhoek's shadow.

On Charles Atwood Kofoid (1865-1947): The good, the bad, and the ugly.

Charles Atwood Kofoid was a scientist of considerable stature and a key figure in the development of protistology in the United States of America during first half of the 20th century. Today he is known mainly for his detailed taxonomic monographs on protists of the marine plankton, specifically dinoflagellates and tintinnid ciliates. Lesser known today is the wide range of Kofoid's work in protistology. Little known is his responsibility for one of the great mistakes of protistology: the existence of a protistan nervous system, the "neuromortorium". Largely unknown is Kofoid's enthusiastic involvement in the eugenics movement. Here, following a brief biography, I will provide a review of Kofoid's enduring contribution to protistology, "the good", then the story of the neuromotorium, "the bad", and finally an account of Kofoid's implication in the eugenics movement, "the ugly".

On Edouard Claparède and Johannes Lachmann (Clap & Lach) and their "Etudes sur les Infusoires et les Rhizopodes".

Accounts are given of the lives and careers of Edouard Claparède (1832-1871) and Johannes Lachmann (1832-1860), the authors of the landmark work of 19th century protistology "Etudes sur les Infusoires et les Rhizopodes", published in 3 parts in 1859, 1860 and 1861. Accounts are also given on the origin of the monograph, the relationship of Claparède and Lachmann with Ernst Haeckel, and Claparède's role as a promoter of Darwin's theories. Suggestions as to how to properly cite the monograph of Claparède and Lachmann are provided, as well as a supplementary file listing the protist species currently accepted as having been first described in their monograph.

Protistological science dissemination.

It is rare to meet protistologists who are not passionate about their study subject. The vast majority of people, however, never get the chance to hear about the work of these researchers. Although every researcher working on protists is likely to be aware of this situation, efforts made and tools employed for dissemination of knowledge are rarely documented. Following a proposal by the Italian Society of Protistology, a workshop at the 2019 VIII European Congress of Protistology in Rome, Italy, was dedicated to protistological knowledge dissemination. Through the many interventions, we discovered the diversity of efforts to reveal the protistan world to the general public, including museum exhibitions and activities, public understanding of science events, citizen science projects, specific book publications, the use of protists in teaching at all levels from primary school children to university undergraduate students, and to a global audience via social media. The participation of the workshop delegates in the discussions indicated that presentations on the wonderful world of protists to the public not only increase the visibility and accessibility of protistology research but are also very important for the scientific community. Here we report on some of the key aspects of the presentations given in the dissemination workshop.

Protist diversity and function in the dark ocean - Challenging the paradigms of deep-sea ecology with special emphasis on foraminiferans and naked protists.

The dark ocean and the underlying deep seafloor together represent the largest environment on this planet, comprising about 80% of the oceanic volume and covering more than two-thirds of the Earth's surface, as well as hosting a major part of the total biosphere. Emerging evidence suggests that these vast pelagic and benthic habitats play a major role in ocean biogeochemistry and represent an "untapped reservoir" of high genetic and metabolic microbial diversity. Due to its huge volume, the water column of the dark ocean is the largest reservoir of organic carbon in the biosphere and likely plays a major role in the global carbon budget. The dark ocean and the seafloor beneath it are also home to a largely enigmatic food web comprising little-known and sometimes spectacular organisms, mainly prokaryotes and protists. This review considers the globally important role of pelagic and benthic protists across all protistan size classes in the deep-sea realm, with a focus on their taxonomy, diversity, and physiological properties, including their role in deep microbial food webs. We argue that, given the important contribution that protists must make to deep-sea biodiversity and ecosystem processes, they should not be overlooked in biological studies of the deep ocean.

Unmasking "The Eldest Son of The Father of Protozoology": Charles King.

In 1703 two articles appeared in the Transactions of the Royal Society, authored by an unnamed gentleman. The articles, with deference to Leeuwenhoeck, described recent observations made with a microscope. Clifford Dobell, in his biography of Leeuwenhoeck, remarked at length on the extraordinary quality of the illustrations and descriptions of "animalcules". He declared the anonymous author to be the scion and master draughtsman of Leeuwenhoeck's followers. Still today, one of the illustrations is credited with being the first unambiguous depiction of a diatom. Here I present evidence that the anonymous author was Charles King of Staffordshire and evidence of his talent. John Hill is often credited for the first naming and illustrating Paramecium and other ciliates in his 1752 book, but it has been claimed repeatedly that he copied the anonymous 1703 illustrations without attribution. Here, the illustrations from 1703 and 1752 are given, and casual examination suffices to show not only that the illustrations were copied, but also that the 1703 illustrations (and text descriptions) of Charles King are of a far higher quality than those of John Hill. Although very little is known about Charles King, he deserves recognition as a pioneer of protistology.

From the Popularization of Microscopy in the Victorian Age: A Lesson for Today's "Outreach".

In the latter half of the Victorian Age (1837-1901) microscopy was introduced as popular past-time. Many books were published aimed at general audiences, both adult and juvenile, on microscopy. Here I consider 5 of these popular books of particular interest to protistologists as they included presentations of 'infusoria' or 'animalcules'. I focus on the scientific backgrounds of the authors, from what we know of them, and the approaches taken to engage the reader based on their texts and illustrations. The possible lesson to be drawn from this exercise concerns our oft-mandated efforts in "Outreach". The methods used by 19th century popularizes of the 'wonders of the microscopic world' can likely be used today. They appealed to the imagination, to empowerment, and gave very practical instructions on how to see the invisible. I conclude that we should likely target the very young and describe our organisms with the enthusiasm that brought us to Protistology to begin with, but which we often conceal.

Past President's Address: Protists of the Mesopelagic and a Bit on the Long Path to the Deep Sea.

The deep sea has long been a mysterious and attractive habitat for protistologists. However, logistical difficulties severely limit sampling opportunities. Consequently, our knowledge of the protists in the deep sea, (arguably the largest habitat on earth), is relatively sparse. Here, we present a unique time-series concerning three different protist taxa that share only the characteristics of being relatively large, robust to sampling, and easily identifiable to species level using light microscopy: tintinnid ciliates, phaeogromid cercozoans (e.g. Challengerids) and amphisolenid dinoflagellates. We sampled a near-shore deep water site in the N.W. Mediterranean Sea at 250 m depth over a 2-yr period at approximately weekly intervals from January 2017 to December 2018. To our knowledge, no previous studies have employed sampling on a similar time scale. We found taxa that appear to be restricted to deep waters, distinct seasonal patterns of abundance in some taxa, and in others nonseasonal successional patterns. Based on data from sampling following a flash flood event, the Challengerid population appeared to respond positively to a pulse of terrigenous input. Some of the distinct mesopelagic tintinnid ciliates and amphisolinid dinoflagellates were also found in two samples from the North Atlantic mesopelagic gathered from near the Azores Islands in September 2018. We conclude that there are a variety of protist taxa endemic to the mesopelagic, that the populations are dynamic, and they may be widely distributed in the deep waters of the world ocean.

The Villefranche Strombidium sulcatum: A review.

The marine oligotrich ciliate Strombidium sulcatum, the best known marine oligotrich of the marine microozoplankton, was first cultured in Villefranche-sur-Mer 35 years ago. Cultures were maintained from 1983 to 2003 and used in 22 studies investigating a very wide variety of questions. Here we review the major findings of these studies and underline their contributions to our knowledge of planktonic ciliate ecology and microbial ecology in general. We conclude with the observation that while ecophysiology has apparently fallen out of fashion, culture work will likely return as an invaluable resource in our present 'omics' era.

The epibiotic life of the cosmopolitan diatom Fragilariopsis doliolus on heterotrophic ciliates in the open ocean.

Diatoms are a diverse and ecologically important group of phytoplankton. Although most species are considered free living, several are known to interact with other organisms within the plankton. Detailed imaging and molecular characterization of any such partnership is, however, limited, and an appraisal of the large-scale distribution and ecology of such consortia was never attempted. Here, observation of Tara Oceans samples from the Benguela Current led to the detection of an epibiotic association between a pennate diatom and a tintinnid ciliate. We identified the diatom as Fragilariopsis doliolus that possesses a unique feature to form barrel-shaped chains, associated with seven different genera of tintinnids including five previously undescribed associations. The organisms were commonly found together in the Atlantic and Pacific Ocean basins, and live observations of the interaction have been recorded for the first time. By combining confocal and scanning electron microscopy of individual consortia with the sequencing of high-resolution molecular markers, we analyzed their distribution in the global ocean, revealing morpho-genetically distinct tintinnid haplotypes and biogeographically structured diatom haplotypes. The diatom was among the most abundant in the global ocean. We show that the consortia were particularly prevalent in nutrient-replete conditions, rich in potential predators. These observations support the hypothesis of a mutualistic symbiosis, wherein diatoms acquire increased motility and tintinnids benefit from silicification through increased protection, and highlight that such associations may be more prevalent than currently appreciated.