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COCCIDIA

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Originally appearing in Volume V06, Page 618 of the 1911 Encyclopedia Britannica.
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COCCIDIA , an important See also:

order of See also:Sporozoa See also:Ectospora, parasites possessing certain very distinctive characters. With one or two possible exceptions, they are invariably intracellular during the entire trophic See also:life of the individual. They always attack See also:tissue-cells, usually of an epithelium, and never See also:blood-corpuscles. Correlated with the advanced degree of See also:parasitism, there is a See also:complete See also:absence of specialization or differentiation of the See also:cell-See also:body, and the trophozoite is quite incapable of any See also:kind of See also:movement. In all cases, so far as known, the life-See also:cycle is di-genetic, an asexual See also:generation (produced by schizogony) alternating with a sexual one (gametogony). After conjugation of two highly-differentiated gametes has taken See also:place, a resistant oocyst is formed, which provides for the dispersal of the See also:species; inside this sporogony (spore- and sporozoite-formation) goes on. See also:Hake (1839) was, perhaps, the first to describe a Coccidian, but he regarded the parasites as pathological cell-products. In 1845 N. Lieberkuhn pointed out the resemblances See also:History. to See also:Gregarines, with which organisms he considered Coccidia to be allied. A See also:year later, H. Kloss proved the existence of similar parasites in the See also:snail, and attempted to construct their life-history; this See also:form was subsequently named Klossia helicina by A. See also:Schneider.

The asexual See also:

part of the life-cycle was first described by Th. Eimer in 1870, for a Coccidian infesting the See also:mouse, which was afterwards elevated by Schneider into a distinct genus Eimeria. The generic name Coccidium was introduced by R. Leuckart in 1879, for the See also:parasite of the See also:rabbit. It was many years, however, before the See also:double See also:character of the life-cycle was realized, and the ideas of L. and R. See also:Pfeiffer, who first suggested the possibility of an See also:alternation of generations, for a See also:long See also:time found no favour. In the first See also:decade of the loth See also:century See also:great progress was accomplished, thanks largely to the researches of F. Schaudinn and M. Siedlecki, who first demonstrated the occurrence of sexual conjugation in the See also:group; and the Coccidian life-history is now one of the best known among Sporozoa. Coccidia appear to be confined' to four great phyla, Vertebrates, ' A curious organism, parasitic in a gregarine, has lately been described by Dogiel as a coccidian, and termed Hyalosphaera. Molluscs,ArthropodsandAnnelids; the first named group furnishes by far the most hosts, the parasites being frequently met with in domestic animals, both birds and mammals. Following from the casual method of infection, the epithelium of the gut or of its appendages (e.g. the See also:liver [See also:Plate I., fig.

I]) is a very See also:

common seat of the parasitic invasion. But in many cases Coccidia are found in other See also:organs, to which they are doubtless carried by lymphatic or circulatory channels. In Molluscs, they often occur in the kidneys (fig. 2); in See also:Insects, they are met with as " coelomic " parasites, the See also:fat-bodies, pericardial cells, &c., being a favourite See also:habitat; even the testis is not See also:free from their attentions in one or two instances, though the ovary appears always immune. The parasite invariably destroys its See also:host-cell completely. The latter is at first stimulated to abnormal growth and activity and becomes greatly hypertrophied, the See also:nucleus also undergoing karyolytic changes (fig. 4). The fatty materials elaborated by the host-cell are rapidly used up by the Coccidian, as nourishment; and at length the weakened and disorganized cell is no longer able to assimilate but See also:dies and is gradually absorbed by the parasite, becoming reduced to a See also:mere enclosing skin or envelope. In some cases (ex. Cyclespora caryolytica of the See also:mole) the parasite is actually intranuclear, the nucleus becoming greatly swollen and transformed into a huge vacuole containing it. The effects of a Coccidian infection upon the host as a whole depend largely upon the extent to which endogenous multiplication of the parasites takes place. On the one See also:hand, schizogony may be so limited in extent as not to cause appreciable injury to the host.

This seems to be often the See also:

case in forms infecting Molluscs and Arthropods. On the other hand, where schizogony is rapid and prolonged, the results are often serious. For, although any one individual only causes the See also:death of a single host-cell, yet the number of the parasites may be so enormously increased by this means, that the entire affected epithelium may be overrun and destroyed. Thus are occasioned See also:grave attacks of coccidiosis, characterized by severe See also:enteritis and See also:diarrhoea, which may end fatally. In the case of the Vertebrates, secondary causes, resulting from the stoppage of the bile ducts, also help to produce death. There is, however, one See also:factor in the endangered See also:animal's favour. Schizogony cannot go on indefinitely; it has a limit, dependent upon the See also:supply of host-cells, and consequently of nutriment, available. As this shows signs of becoming exhausted, by the rapid multiplication of the parasites, the latter begin to make preparations for the exogenous cycle, inaugurated by gametogony. When conjugation has taken place and sporogony is begun, the danger to the host is at an end. So that, if the acute See also:stage of the disease is once successfully passed, the regenerative capacity of the epithelium may be able to restore something like See also:equilibrium to the deranged See also:metabolism in time to prevent collapse. Coccidium schubergi, parasitic in the See also:intestine of a See also:centipede (Lithobius f orficatus), may be taken as an example of a Coccidian Morpho- life-history (see Schaudinn, goo): some of the more logy and important See also:variations exhibited by other forms will be life- noted afterwards. The trophozoite, or actively-grow- history. See also:ing parasite, is an See also:oval or rounded body (fig.

3, I.). The See also:

general cytoplasm shows no differentiation into ectoplasm and endoplasm; it is uniformly alveolar in character. The nucleus is relatively large, and possesses a distinct membrane and a well-marked reticulum in which are embedded grains of chromatin. Its most conspicuous feature is the large deeply-staining karyosome, which consists of the greater part of the chromatin of the nucleus intimately See also:bound up with a plastinoid basis. When fully grown, the trophozoite (now a schizont) undergoes schizogony. Its nucleus divides successively to form a number of nuclei, which travel to the periphery, and there become more or less regularly disposed (fig. 3, II. and III.). The See also:protoplasm in the neighbourhood of each next grows out, as a projecting bud, carrying the nucleus with it. In this manner are formed a number of See also:club-shaped bodies, the merozoites, which are at length set free from the See also:parent-body (IV.), leaving a certain amount of residual cytoplasm behind. By the rupture of the disorganized host- cell,' the fully-formed merozoites are liberated into the intestinal lumen, and seek out fresh See also:epithelial cells. Each is more or less sickle-shaped, and capable of active movements. Once inside a new host-cell, the merozoite grows to a schizont again.

After this course has been repeated several times, gametogony sets in, the trophozoites growing more slowly and becoming the parent-cells of the sexual elements (gametocytes), either male individuals (microgametocytes) or See also:

female ones (megagametocytes). A microgametocyte (fig. 3, VI. a) is characterized by its dense but finely reticular or alveolar cytoplasm, very different from the loose structure of that of a schizont. The male elements (microgametes) are formed in a manner essentially comparable to that in which the formation of merozoites takes place. Al-though the details of the nuclear changes and divisions vary somewhat, the end-result is similar, a number of little nuclear agglomerations being evenly distributed at the See also:surface (VII. d). Each of these elongates considerably, becoming See also:comma-shaped and projecting from the gametocyte. Nearly all the body of the male gamete (VIII. a) consists of chromatin, the cytoplasm only forming a very delicate See also:zone or envelope around the nucleus. From the cytoplasm two long See also:fine flagella grow out, one of which originates at the anterior end, the other, apparently, at the hinder end, acting as a See also:rudder; but it is probable that this also is See also:developed at the anterior end and attached to the See also:side of the body. Bymeans of their flagella the numerous microgametes break loose from the body of the microgametocyte and swim away in See also:search of a female See also:element. A megagametocyte (VI. Y) is distinguished by its rather different shape, being more like a See also:bean than a See also:sphere until ripe for maturation, and by the fact that it stores up in its cytoplasm quantities of reserve nutriment in the form of rounded refringent plastinoid grains. Each female gametocyte gives rise to only a single female element (megagamete), after a See also:process of nuclear See also:purification.

The karyosome is expelled from the nucleus into thecytoplasm, where it breaks up at once into fragments (VII. ~). Meanwhile the gametocyte is becoming spherical, and its changes in shape aid in setting it free from the shrivelled host-cell. The fragments of the karyosome, which are, as it were, squeezed out to the exterior, exert a powerful attraction upon the micro-gametes, many of which swarm See also:

round the now mature mega-gamete. The female nucleus (pronucleus) approaches the surface of the cell (VIII. Y), and at this spot a little clear cytoplasmic prominence arises (See also:cone of reception). On coming into contact with this protuberance (probably attracted to it by the female pronucleus), a microgamete adheres. Partly by its own movements and partly by the withdrawal of the cone of attraction, the male penetrates into the female element and fertilization is accomplished. Only one microgamete can thus pass into the megagamete, for immediately its entry is effected a delicate membrane is secreted around the copula (zygote), which effectually excludes other less fortunate ones. This membrane rapidly increases in thickness and becomes the oocyst (IX.), and the copula is now ready to begin sporogony. Sporogony goes on indifferently either inside the host or after the cyst has been passed out with the faeces to the exterior. The definitive nucleus of the zygote (resulting from the intimate See also:fusion of the male and female pronuclei, by means of a somewhat elaborate " fertilization-spindle " [XI) gives rise by successive See also:direct divisions to four nuclei (XII.), around which the protoplasm becomes segregated; these segments form the four sporoblasts.

Around each sporoblast two membranes are successively secreted (exospore and endospore),which constitute the sporocyst(XIII.); the sporocyst and its contents forming the spore. The nucleus of each spore next divides, again directly, and this is followed by the See also:

division of the cytoplasm. As a final result, each of the four spores contains two germs (sporozoites), and a certain amount of residual protoplasm (fig.3, XIV.); this latter encloses a viscid, vacuole-like body, which See also:aids in the subsequent dehiscence of the sporocyst. On being eaten by a fresh host, the See also:wall of the oocyst is dissolved at a particular region by the It is important to See also:note that in schizogony there is never any cyst or cyst-membrane formed around the parasite. Habitat: effects on host. See also:digestive juices, which are thus enabled to reach the spores and cause the rupture of the sporocysts. As the result of instructive experiments, Metzner has shown that it is the pancreatic and not the gastric juice by which this liberation of the germs is effected. The liberated sporozoites creep out and proceed to infect the epithelial cells. The sporozoites (XV.) are from 15–20 µ long by 4–6 i wide; they are fairly similar to merozoites in form, structure and behaviour, the See also:chief point of distinction being that they have no karyosome in the nucleus (cf. above). Comparing the life-cycle of other Coccidia with that just described", a greater or less degree of modification is frequently met with. In the process of schizogony two orders of division sometimes occur; the parent-schizont first divides up into a varying number of rounded daughter-schizonts (schizontocytes), each of which gives rise, in the usual manner, to a cluster of merozoites,' which thus constitute a second order of cells. Siedlecki (1902) has found this to be the case in Caryotropha mesnilii (fig.

4); and See also:

Woodcock (1904) has shown that it is most probably really the same process which See also:Smith and See also:Johnson (1902) mistook for sporogony when originally describing their Coccidian of the mouse, Klossiella. In Caryotropha, a perfectly similar See also:state of affairs is seen in the formation of microgametes from the microgametocyte; this is additionally interesting as showing that this process is neither more nor less than male schizogony. Coming to the sexual generation, considerable variation is met with as regards the See also:period in the life-history when sexual differentiation first makes its See also:appearance. Sexuality may become evident at the very beginning of schizogony, as, e.g. in Adelea ovata (Siedlecki, 1899), where the first-formed schizonts (those developed from the sporozoites) are differentiated into male and female (micro- and mega-schizonts) (see Plate II., fig. 5). Correspondingly, the merozoites, to which they give rise, are also different (micro- and mega-merozoites). In one or two cases sexuality appears even earlier in the cycle, and has thus been carried still farther back. The Coccidia, as a whole, have not developed the phenomenon of association of the sexual individuals See also:prior to gamete-formation which is so characteristic of Gregarines. Their method of endeavouring to secure successful sporulation, and thus the survival of the species, has been rather by the extreme specialization of the sexual process. In place of many female elements, which the See also:primitive or ancestral forms may be assumed to have had,2 there is always, See also:save possibly for one exception,3 only a single relatively huge megagamete formed, which offers a comparatively easy See also:goal for one of the many microgametes. Nevertheless in the effort to render fertilization absolutely certain, a few Coccidia have acquired (secondarily) the See also:power of associating; a state of things which enables those forms, moreover, to effect an See also:economy in the number of male gametes, only three or four being developed. Instances are seen in Adelea mesnili (See also:Perez, 1903), A. ovata (fig.

6), and Klossia helicina (Siedlecki, 1899). It is very interesting to note that, in the two last cases, unless this association of the microgametocyte with the megagametocyte occurs, neither can the former produce male elements (micro-gametes) nor can the female individual maturate and become ready for fertilization. (Concerning this question of association see also GREGARINES.) In sporogony, great variation is seen with respect to the number of spores and sporozoites formed; and, as in Gregarines, these characters are largely used for purposes of See also:

classification, under which heading they are better considered. Usually, the spores (fig. 7) are quite See also:simple in outline, and not produced into i The merozoites are frequently arranged like the staves of a barrel—whence the See also:term barillet, which is frequently used. 2 In Cyclospora, Schaudinn (1902) has noted certain abnormal cases of the persistence and further multiplication of the " reduction-nuclei " of the female element (i.e. the nuclear portions given off during maturation), followed by multiple fertilization. This occurrence points strongly to the conclusion that there were originally many female gametes (cf. also the sporoblasts of Gregarines). The remarkable forms parasitic in Cephalopods (of See also:late known as Eucoccidium), if still ranked with the Coccidia, furnish an exception (see below).spines or processes; exceptions are found, however, in a few instances (e.g. Minchinia chitonis). In one case (Coccidium mitrarium), the oocyst itself, instead of being spherical, is curiously shaped like a See also:mitre. The life-history as a whole is invariably undergone in a single host, i.e. there is no alternation of true hosts.4 Schaudinn, in his See also:work on the Coccidia of Lithobius (1900), showed that the oocysts expelled with the faeces may be eaten by See also:wood-lice (Oniscus), but when this happens they pass through the intestine of the wood-See also:louse unaltered, the latter not being an intermediate host but merely a See also:carrier. The order Coccidiidea is divided into four families, characterized by the number of sporocysts (if any) found in the oocyst.

Fam. ASPOROCYSTIDAE, Leger. No sporozoites are Ciassififormed in the oocyst, the sporozoites being unenclosed cation. (gymnospores). Genus, Legerella, Mesnil. This genus actually conforms to Aime Schneider's See also:

original See also:definition of Eimeria, which was founded on what were really the schizogonous generations of other forms, then thought to be distinct. In view of the great confusion attending the use of this name, however, Mesnil (1900) has suggested the new one here adopted. Two species known, L. nova and L. testiculi, both from different species of Glomeris, a Myriapod; the former inhabits the Malpighian tubules, the latter the testis. Fam. DISPOROCYSTIDAE, Leger. The oocyst contains 2 spores. Genus I.

Cyclospora, A. Schneider. Spores dizoic, i.e. with two sporozoites. C. glomericola, from the intestinal epithelium of Glome-is, and C. caryolytica, from the intestinal epithelium of the mole, intranuclear. Genus 2. Diplospora, Labbe. Spores tetrazoic. D. lacazei, from many birds, is the best-known species; and others have been de-scribed from different See also:

Sauropsida. D. lieberkuhni is an interesting form occurring in the kidneys of the See also:frog, which it reaches by way of the circulation. Genus 3. Isospora, Schn. Spores polyzoic.

Founded for I. rara, parasitic in the See also:

black slug (Limax cinereo-See also:niger). Many authors consider that Schneider was mistaken in attributing many sporozoites to this form, and would unite with it the genus Diplospora. Fam. TETRASPOROCYSTIDAE, Leger. The oocyst contains 4 spores. Genus I. Coccidium,5 Leuckart. The spores are dizoic and the sporocysts rounded or oval. A very large number of species are known, mostly from Vertebrate hosts. C. cuniculi (=C. oviforme) from the rabbit (intestine and diverticula), but also occurring some-times in other domestic animals; C. falciformis, from the mouse; C. faurei from See also:sheep; and C. schubergi, from Lithobius (a centipede), are among the best-known forms. All of them may cause disastrous epidemics of coccidiosis. Genus 2.

Paracoccidium, Laveran and Mesnil. This genus is distinguished from Coccidium by the fact that the sporocysts become dissolved up in the oocyst, thus leaving the 8sporozoites unenclosed, recalling the See also:

condition in Legerella. P. prevoti, unique species, from the frog's intestine. Genus 3. Crystallospora, Labbe. Spores also dizoic, but having the form of a double See also:pyramid. C. crystalloides from a See also:fish, Motella tricirrata. Genus 4. Angeiocystis, Brasil. Apparently 6 sporozoites, but the only species, A. audouiniae, has only been briefly described; from a Polychaete (Audouinia). Fam. POLYSPOROCYSTIDAE, Leger.

The oocyst contains numerous spores. There are several genera with monozoic spores, characterized by variations in the form and structure of the sporocysts, e.g. Barroussia, Schn. (fig. 8), Echinospora, Leger, and Diaspora, Leger; most of these forms are from Myriapods. Genus Adelea, Schn. Dizoic spores; sporocysts round or oval, See also:

plain. Several species are included in this well-known genus, among them being A. ovata, A. mesnili, A. dimidiata; most of them are parasitic in Insects or Myriapods. Genus Minchinia, Labbe. Dizoic spores; the sporocysts are produced at each See also:pole into a long filament. M. chitonis, from the liver of See also:Chiton (See also:Mollusca). Genus Klossia, Schn.

The spores are tetrazoic (or perhaps polyzoic). K. helicina from the See also:

kidney of various See also:land-snails is the best-known form. Usually said to have 5 to 6 spores, but Mesnil considers that the normal number is 4, as is the case in another species, K. soror. Genus Caryotropha, Siedlecki. Many spherical spores (about 2o) 4 Again with the exception of Eucoccidium. b Purists in systematic nomenclature maintain that this name should be relinquished in favour of Eimeria, since the latter was the first legitimate generic name given to a Coccidian. But one See also:reason against the use of Eimeria has been stated already (it should be used for E. (Legerella) nova, if anywhere); and in addition, the word Coccidium and its important derivatives are now so universally established that it would be little See also:short of ridiculous to displace them. each with 12 sporozoites. C. mesnilii, unique species, from the spermatogonial (testis) cells of Polymnia (a Polychaete). An interesting point in the schizogony is the formation of gchizontocytes (see above). A Coccidian parasitic in the kidneys of the mouse has been de-scribed by Smith and Johnson (19o2) and named by them Klossiella, on the ground that it possessed many spores, each with about 20 sporozoites.

Woodcock has shown, however, that the authors were in all See also:

probability dealing with a similar modification of schizogony to that which obtains in Caryotropha. The sporogony of this form (and hence its systematic position) remains at See also:present, there-fore, quite unknown. There are several doubtful or insufficiently known genera, e.g. Bananella, Goussia, Hyaloklossia, Gonobia, Pfeifferella and Rhabdospora, many of which probably represent only schizogonous generations of other forms. (For See also:information concerning these see Labbe, 1897.) Lastly it remains to mention the extremely interesting forms parasitic in Cephalopods. For some years these have provided a fruitful source of discussion to systematists. Here it may be stated simply that their systematic position and nomenclature were thought to have been finally settled by the researches of Jacquemet (1903) and See also:Labe (1902) in the following terms: Genus Eucoccidium. Lillie (syn. Leggerina Jacq.), Coccidia possessing polysporous oocysts and lacking schizogony, parasitic in Cephalopods. Two well-known species: E. eberthi (Labbe), (= Benedenia seu Klossia e. seu octopiana), parasitic in See also:Sepia, which is tri- or tetra-zoic; and E. octopianum (Schn.), (syn. Benedenia seu Klossia o.) from See also:Octopus, which is polyzoic, having Io to 12 sporozoites. In both forms cysts containing megaspores and megasporozoites, and others containing microspores and microsporozoites are found, considered as representing sexual differentiation thrown back to the very earliest stages of the life-cycle.

Quite recently much additional See also:

light has been thrown upon our knowledge of these parasites, including a new one, E. jacquemeti. Moroff 1906) has shown that not one but many megagametes are formed, and fertilized by the microgametes. For this reason he regards them as Gregarines rather than Coccidia. Further, Leger and Duboseq (1906) have found that the characteristic coelomic parasites (Aggregata) of See also:Crustacea, generally regarded as gymnosporous Gregarines (i.e. Gregarines in which the sporozoites are naked) constitute in reality nothing more or less than a schizogonous generation of these Cephalopodan parasites, which have thus an alternation of true hosts. The ripe sporocysts from the Cephalopod are eaten by a particular crab (e.g. See also:Portunus or Inachus, according to the parasite), the sporozoites are liberated and See also:traverse the mucous membrane of the intestine, coming to See also:rest in the surrounding lymphatic layer. Here a large " cyst " is formed, projecting into the body-cavity, the contents of which give rise to a great number of merozoites. On the crab being devoured by the right species of Cephalopod, the merozoites doubtless give rise to the sexual generation again. As the name Aggregata is much the older, and as, moreover, there is no longer any reason to retain that of Eucoccidium, these parasites must in future receive the former generic appellation. With regard to the various specific names, however, they remain quite unsettled until the life-history is properly worked out in different cases (see also GREGARINES). It seems to the writer a much more open question than Moroff and Leger and Duboseq apparently suppose, whether these parasites are to be relegated to the Gregarines.

For undoubtedly they have many Coccidian features, and on the other hand they differ in many ways from Gregarines. The chief feature of agreement with the latter order is the See also:

possession of many female gametes. As already said, there can be little doubt that this was the condition in the Coccidian ancestor, and it is by no means impossible that one or two forms existing at the present See also:day remain primitive in that respect. On the other hand, the advanced character of the parasitism (the parasites remaining intracellular up to and including gamete-formation); the entire lack of the characteristic feature of association; the schizogony, which is only a very rare occurrence in Gregarines, and which, in the present case, strongly suggests the process in Caryotropha and Klossiella; and, last but not least, the varying number of the sporozoites (3 in one form, 10-15 in others), which is very different from the almost See also:constant slumber (8) in Gregarines, are all characters in which these forms agree with Coccidia and not with Gregarines. Having regard to these points, the writer is inclined, for the present, to consider Aggregate as an off-shoot rather from the Coccidian than from the Gregarine See also:branch of the Ectosporan See also:tree. C.R. See also:Soc. Biol. 50, p. 1139, 1898; A. Laveran and F. Mesnil, " Sur deux Coccidies intestinales de la Rana esculenta," op. cit.

54, p. 857, 9 See also:

figs., 1902; A. Laveran and F Mesnil, " Sur la Coccidie trouvee dans le See also:rein de la Rana esculenta, &c.," C.R.Ac. Sci. 135, p. 82, 10 figs., 1902; A. Laveran and F. Mesnil, " Sur quelques Protozoaires parasites d'une tortue, &c." t. c. p. 609, 14 figs., 1902; L. Leger, Sur une nouvelle Coccidie microgametes cities," op. cit., 127, p. 418, 1898; L. Leger, " Sur la morphologie et le developpement See also:des microgametes des Coccidies," See also:Arch. zool. exp.

(N. et R.) (3), 6, 1898; L. Leger, " Essai sur la classification des Coccidies, &c.," See also:

Ann. See also:Mus. Nat. Hist., Marseille (2), See also:Bull. i. p. 71, 4 pls., 1898; L. Leger " Sur la presence d'une Coccidie coelomique chez Olocrates, &c.," Arch. zool. exp. (N. et R.) (3), 8, p. i., 1900; L. Leger, " Sur le genre Eimeria et la classification des Coccidies," C.R. See also:Sac, Biol. 52, p. 575, 1900; L.

Leger and 0. Duboseq, " Recherches sur See also:

les Myriapodes de See also:Corse et leurs parasites," Arch. zool. exp. (4), 1, p. 307, 24 figs., 1903; L. Leger and O. Duboseq, " Sur revolution des Gregarines gymnosporees des Crustaces," C.R.Ac. Sci. 142, p. 1225, 1906; L. Leger and O. Duboseq, " L'See also:Evolution dune Aggregate de la See also:seiche chez le Portunus depurator," C.R. Soc.

Biol. 6o, p. See also:

tool, 1906; M. Liihe, " Uber Geltung and Bedeutung der Gattungsnamen Eimeria and Coccidium," C. B. Bakter (I) 31 Orig, p. 771, 1902; C. B. Bakter, " See also:Die Coccidien-Literatur der letzten vier Jahre," Zool. Centrlbl. to, 45 pp., 1903; F. Mesnil, " Sur la conservation du nom generique Eimeria, &c.," C.R. Soc. Biol.

52, p. 603, 1900; F. Mesnil, " Les Travaux recents sur les Coccidies," Bull. Inst. See also:

Pasteur, i. pp. 473, 505, 1903; R. Metzner, " Untersuchungen an Coccidium cuniculi," Arch. Protistenk. 2, p. 13, pl. H. 1903 ; G.

Moussu and G. Marotel, " La Coccidiose du mouton et son parasite," Arch. Parasitol. 6, p. 82, 10 figs., 1902 ; T. Moroff, " Sur 1`e, olution des pretendues Coccidies des Cephalopodes," C.R.Ac. Sci. 142, p. 652, 1906; C. Perez, " Le Cycle evolutif de l'Adelea mesnili, &c.," Arch. Protistenk. 2, p.

1, pl. 1, 1903; F. Schaudinn, " Untersuchungen fiber den Generationswechsel bei Coccidien," Zool. Jahrbiicher (Anat.) 13, p. 197, 4 pls., 1900; F. Schaudinn, " Studien uber krankheitserregende Protozoan—I. Cyclospora caryolytica, &c.," Arb. kais. Gesundh.-amte, 18, p. 378,.2 pls., 1902; M. Siedlecki, " See also:

Reproduction sexuee . chez Coccidium proprium," C.R. Soc. Biol.

5o, p. 664, figs., 1898; M. Siedlecki, )Etude cytologique . . . de la Coccidie de la seiche, &e.," Ann. Inst. Pasteur, 12, p. 799, 3 pls., 1898; M. Siedlecki, " Etude cytologique . de Adelea ovata," op. cit. 13, p. 169, 3 pls., 1899; M. Siedlecki, " Cycle evolutif de la Caryotropha mesnilii, &c.," Bull, Ac. Cracovie, p.

561, 5 figs., 1902; T. Smith and H. P. Johnson, " On a Coccidian (Klossiella muris, gen. et spec. nov.), &c.," J. exp. Med. 6, p. 303, 3 pls., 1902 ; H. M. Woodcock, " Notes on Sporozoa, I. On Klossiella muris, &c.," Q.J. micr. Sci. 48, p.

153, 2 figs., 1904. (H. M.

End of Article: COCCIDIA

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