Notes: SYNOPSIS. A sequence of developmental stages of Plistophora hyphessobryconis Schaperclaus, a microsporidian protozoan parasite of the muscular tissue of several species of freshwater fishes, was studied with the electron microscope. The youngest stages observed, ca. 4 × 2 μ, have a single nucleus and their plasm contains only ergastoplasmic lamellae and ribosomes. They are surrounded by a halo of lysed host tissue. They increase in volume to become large sporonts with a great number of nuclei and a thick, 2-layered membrane. Thru schizogony, a corresponding number of sporoblasts is produced within this pansporoblast membrane. Sporoblasts start to develop a thick spore membrane, and a number of smooth-membraned vesicles appear in the plasm. These vesicles fuse to make the outer membrane of the filament. Later, its inner structures originate—the axial electron-dense substance, filling the hollow lumen of the filament, and a middle, electron-transparent layer. The structure of the filament is discussed in relation to its function and with regard to the findings of other authors.The polaroplast is a laminated structure, originating possibly by transformation of endoplasmic reticulum; the polar cap forms its apical part. The cap is also lamellar; its substance reaches into the lumen of the filament for a certain distance. No micropyle was discovered in the shell; the filament is fastened to the polar cap. These observations on microsporidian development and on the structure of their spores are compared with similar data on myxosporidian species. Such a comparison speaks clearly in favor of the complete taxonomic separation of the Microsporidea from the Myxosporidea, the latter being quite different also from other sporozoa sensu lato.

Notes: The literature involving the genus Tetrahymena has become so voluminous in recent years that some consolidation of it appears advisable. Through 1953 well over 500 papers, scattered through more than 100 scientific journals, have been devoted in whole or in part to studies in which species and strains of this genus, under a variety of names, have been employed as one of the experimental animals. Nearly half of these works are cited directly in the present paper. The major areas of research in which these ciliates have been used to advantage include physiology and biochemistry, containing nearly 60% of all the papers, cytology and taxonomy, and three smaller fields arbitrarily designated as cytogenetics, morphogenesis, and parasitism. Tetrahymena's sustained popularity as an object of research may be considered as due primarily to its ability to thrive axenically in a chemically defined nutrient medium and secondarily to such factors as its ubiquity in nature, its ready adaptability to a variety of ecological situations (including endoparasitism), its possession of a relatively primitive and fundamental type of buccal ciliature of considerable phylogenetic significance, and its exhibition of the sexual phenomena of conjugation and autogamy.

Notes: SYNOPSIS. Morphogenesis in the small holotrich ciliate Pseudocohnilembus persalinus has been found to be more complex than that reported to date for any other hymenostome species, at least with respect to the major phenomenon of stomatogenesis. Formation of two anlagen or fields of proliferating kinetosomes in the vicinity of the old oral area initiates the highly autonomous process. Subsequently a number of separate but coordinated morphogenetic movements occur which involve not only the new anlagen and their extraordinary growth and fragmentation but also the bases of the “old” ciliary buccal organelles.Particularly indispensable in our investigation was the Bodian protargol technique which reveals the external ciliature of a properly fixed organism as well as components of its infraciliature. The Chatton-Lwoff silver impregnation method, however, was also very useful in the overall comparative study of the present and related species of ciliates.At one stage in stomatogenesis of Pseudocohnilembus persalinus there is clear evidence of a basic tetrahymenal plan of organization of the buccal ciliature, even though this is not at all apparent in the mature, non-dividing ciliate. Such a revelation underlines the significant value of morphogenetic studies in comparative ciliate systematics, for our findings permit retention of the genus Pseudocohnilembus in the suborder Tetrahymenina of the holotrich order Hymenostomatida. At the same time, however, they necessitate revision of some currently held concepts in the fields of ciliate morphology, taxonomy, and phylogeny.

Notes: SYNOPSIS. An international collection center for type-specimens of protozoa belonging to the subphylum Ciliophora has been set up at the University of Illinois through the cooperation of the Museum of Natural History there. The writer will act as curator of slides deposited in this central collection. Syntypes are solicited from all protozoologists interested in ciliate taxonomy who may possess such specimens. In accordance with provisions of Article 72 of the International Code of Zoological Nomenclature, all material received will be properly handled and indexed and regarded as “the property of science”; preparations will be made available on loan to qualified workers anywhere who need them temporarily for research purposes. Existence of such a type-slide collection should aid in alleviation of a growing number of vexatious problems in the systematics of the ciliate Protozoa at specific and generic levels.

Notes: SYNOPSIS. Stomatogenesis or new mouth formation sensu lato repnts an explicit example of a major morphogenetic phenomenon le life cycle of most ciliate Protozoa. Investigations of the process a number of approaches may yield data of considerable value. The present paper 3 such approaches are treated in some detail.udies of stomatogenesis can be of importance in providing addial information of significance on the structure and physiology a given organism. Five major types or categories of stomatoesis in ciliates are recognized. These are defined and discussed. search related to such an intrinsic value of the phenomenon the K carried out is generally only descriptive, and the most importechnic employed is some method of silver impregnation.a comparative approach is used, then attention may be focused possible homolegies in stomatogenesis as it occurs in diverse ies of ciliates. Such data are (or potentially are) of value not in the practical taxonomy of the organisms involved but also onsideration of phylogenetic and evolutionary interrelationships ing the higher groups comprising the entire subphylum Ciliophora. Such application of comparative studies may well become a very fruitful approach to certain problems in ciliate phylogeny; 2 examples are discussed briefly. Silver impregnation technics are again indispensable.Perhaps stomatogenesis will prove most valuable in the hands of developmental biologists who are seeking to solve 2 of the most intriguing problems in cell biology today: the exact origin of new kinetosomes (or centrioles), and their precise morphogenetic role in the life cycle of a cell or unicellular organism. Since this third approach to the study of stomatogenesis is of necessity a dynamic one, the researcher must employ sophisticated experimental technics to obtain data at the molecular and macromolecular levels of both organization and function. Some progress in this area has already been made, but the availability of “ideal” organisms has perhaps not been as widely realized as it should. Certain of the “higher” ciliates have a mode of stomatogenesis which would lend itself beautifully to fruitful investigation of problems concerning both replication or neoformation of kinetosomes and their possible role in fibrillogenesis in unicellular organisms.

Notes: SYNOPSIS. Confusion has long existed in the literature concerning both the taxonomy and the nomenclature of ciliates belongin: to the astomatid family Haptophryidae. Most of the controversy has centered around the names and concepts of “Haptophrya” and “Sieboldiellina.” The latter name, widely used for certain species found as parasites (endocommensals) of turbellarians, must fall as a junior synonym of the former, which has commonly been restricted to the astomatous ciliate parasites (endocommensals) of various amphibians But the species of “Haptophrya” are then left without a generic vehicle, since Haptophrya Stein, 1867, must, in effect, be used to replace Sieboldiellina Collin, 1911, as the proper generic name of the turhellarian parasites Fortunately a name is available for the amphibian species: Cepedietta Kay, 1942.The problem is further complicated because of the recognition of subfamilial groups, the name of one of these having been formed from Sieboldiellina and having become associated with certain species parasitic in turbellarians. With the realization that, by the international rules of zoological nomenclature, Haptophrya must be used with reference to these particular turbellarian parasites, the subfamilial name associated with the amphibian forms must be changed. We propose Cepediettinae n. nom. in solution of this particular problem. We recognize a third subfamily, Ckpkde's Lachmannellinae, to contain the three remaining acceptable genera comprising the family Haptophryidae: Anndophrya, Lachmanndla, and Steinella.At the generic and specific levels numerous errors of a nomenclatural nature have been committed in the older literature, many unwittingly perpetuated in recent papers. These are all corrected in the present work. For the sake of future clarity we have included a series of figures, both original and from the literature, and have designated neotypes of the two principal species involved in the overall controversy.