The Sporogony and Systematic Position of the Aggregatidæ
Authors: Pixell-Goodricli Helen E. M. 
Published: April 2021

The very noticeable parasites infesting the alimentary canal of many Cephalopods were recorded by Eberth (3) so long ago as 1862. The genus comprising these forms has suffered many changes of nomenclature. In 1875 it was named Benedenia by Schneider (21, Note xiii, p. xl) to include B. octopiana from the octopus, and this generic name was employed so late as 1900 by Schaudinn (20, p. 203). In Schneider’s second paper (22) in 1883 the parasite was referred to throughout as Klossia instead of Benedenia, as the authoi’ stated that he.was convinced that the two genera could not be distinguished. In this Siedlecki followed him in his two papers of 1898 (23 and 24) on the parasites of Sepia, which he considered to be identical with those of the octopus, although he found only three or four sporozoites in a sporocyst, whereas Schneider had described eight to fifteen in Klossia octopiana, and Labbé had already given the specific name of K. eberthi (7) to the species inhabiting Sepia. In a footnote to his second paper, however, Siedlecki (24, p. 800) stated that after seeing Laveran’s work on K. helicina he thought the original name of Benedenia should be readopted. It was then discovered that this name had in 1858 been appropriated for a Trematode genus, therefore Blanchard, in 1900, altered it to Légeria. Jacquement (5) in 1903 pointed out that this had been already applied to a polycystid Gregarine, and again changed the name to Légerina. This, however, was never used; for, in the previous year, after Siedlecki had stated that, like the so-called Eugregarines, these parasites did not appear to undergo Schizogony, the genus had been called Eucoccidium by Lühe (11). By this generic name the parasites were generally known until, in 1906, the excellent researches of Leger and Duboscq (8 and 9) showed that the schizogony, which had been supposed to be absent from the life-history of the genus? took place in the Crab, Portunus, where Frenzel (4) had described it in 1885 as a Gregarine under the name of Aggregata; this name is therefore now universally applied to the genus which I hope to prove is undoubtedly Coccidian in character as assumed by Siedlecki. Moroff (15) in 1906 claimed to have shown that the fertilisation was of the gregarine type; that is, that the macrogametocyte gave rise before fertilisation to a number of small cells, and that these were the true macrogametes, each of which gave, after fertilisation, a single spore. In 1908, in a later work of great length, Moroff (16) admitted that he might have been mistaken in his description of the process of fertilisation, and no longer insisted on these parasites being Gregarines, stating that further investigations were necessary. It was for this reason that, at Prof. Minchin’s suggestion, I undertook this study of Aggregata, which has extended over some years. During this time I have examined Cephalopods, chiefly Sepia, from Plymouth, the Solent, and more recently from the Mediterranean in the neighbourhood of Banyuls-sur-Mer. To the authorities and staff, especially to the Director, Prof. Pruvot, of the Laboratoire Arago, I should like to express my thanks for their hospitality and assistance; also to- Prof. Alinchin, not only for suggesting such an interesting subject for investigation, but for much kind help given me during the years that I have been privileged to work in his Department at the Lister Institute. Since last October the work has been carried on in Oxford, and I am much indebted to Prof. G-. C. Bourne for the kind interest he has shown in the progress of the investigations, and for allowing me the use of a laboratory in his department. My husband, Mr. E. S. Goodrich, has also given me much advice and assistance.