1911 Encyclopædia Britannica/Proteomyxa
PROTEOMYXA, a name given by E. Ray Lankester (Ency. Brit., 9th ed., 1885, art. “Protozoa,”) to a group of Protozoa Sarcodina. The group was really recognized as distinct by Cienkowski and by Zopf, receiving the name of Monadinea from the former; but as this name had been usually applied to Flagellates and even the zoospores are not always provided with flagella, Lankester's name has become more suitable, and has been adopted by Delage and Hérouard (1896) and by Hartog (1906). The group entered to a considerable extent into the “Monera” of Haeckel, supposed (erroneously in most if not all species adequately studied) to possess no nucleus in the protoplasm. The following are the characteristics of the group. Pseudopods usually granular, fine flexible, tapering generally, not freely branching; reproducing sometimes by simple fission, but more frequently by multiple fission in a brood-cyst whose walls may be multiple. Plasmodium formation occasional, but never leading to the formation of a massive fructification: other syngamic processes unknown, and probably non-existent. Encystment, or at least a resting stage at full growth, is very characteristic, and frequently an excretion of granules takes place into the first-formed cyst, whereupon a second inner cyst is formed which may be followed by a third. These brood-cysts, in which multiple fission takes place, may be of two kinds, ordinary and resting, the latter being distinguished by a firm, and usually ornamented and cuticularized cell-wall, and only producing its zoo spores after an interval. Besides, an individual at any age may under unfavourable conditions surround itself with a “hypnocyst,” to pass the time until matters are more suitable to active life, when it emerges unchanged.
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1, Vampyrella spirogyrae, Cienk., amoeba phase penetrating a cell of Spirogyra b, by a process of its protoplasm c, and taking up the substance of the Spirogyra cell, some of which is seen within the Vampyrella a. 2, Large individual of Vampyrella, showing pseudopodia e, and food particles a. The nucleus (though present) is not shown in this drawing. 3, Cyst phase of Vampyrella. The contents of the cyst have divided into four equal parts, of which three are visible. One is commencing to break its way through the cyst-wall f; a, food particles. 4, Archerina boltoni, Lankester, showing lobose and filamentous protoplasm, and three groups of chlorophyll corpuscles. The protoplasm g is engulphing a Bacterium i. 5, Cyst phase of Archerina: a, spinous cyst-wall; b, green-coloured contents. 6, Chlorophyll corpuscle of Archerina showing tetraschistic division. 7. Actinophryd form of Archerina: b, chlorophyll corpuscles. 8, Protogenes primordialis, Haeckel (Amoeba porrecta, M. Schultze), from Schultze's figure. |
From the initial character of the brood-cell on leaving the sporocyst the dividing character of the two orders is taken.
1. Zoosporeae, Zopf. The brood-cells leave the cyst as “Monads” (with one or two flagella). Genera: Pseudospora, Cienk.; Protomonas Cienk.; Diplophysalis, Zopf.; Gymnococcus, Z.; Aphelidium, Z.; Pseudosporidium, Z.; Plasmodiophora, Woronin; Tetramyxa, Goebel.
2. Azoosporeae, Zopf. Genera: Endyonema, Z.; Vampyrella, Cienk. (figs. 1, 2, 3); Leptophrys, Hertw. and Less.; Bursulla, Sorokin; Protogenes, Haeck.(fig. 8); Archerina, Lank. (figs. 4-7); Serosporidium, L. Pfeiffer; Lymphosporidium, Calkins.
Many of the species are endoparasites in living cells, mostly of
Algae or Fungi, but not exclusively. At least two species of
Pseudospora have been taken for reproductive stages in the life history
of their hosts—whence indeed the generic name. Plasmodiophora
brassicae gives rise to the disease known as “Hanburies” or “fingers
and toes” in Cruciferae; Lymphosporidium causes a virulent epidemic
among the American brook-trout, Salvelinus fontinalis. Archerina
boltoni is remarkable for containing a pair of chlorophyll corpuscles
in each cell; no nucleus has been made out, but the chlorophyll
bodies divide previous to fission. It is a fresh-water form. The
cells of this species form loose aggregates or filoplasmodia, like those
of Mikrogromia (Foraminifera, q.v.) or Leydenia (Labyrinthuloidea,
q.v.), &c.
Vampyrella (figs. 1–3) and Enteromyxa also form a compact plasmodium which separates into 1-nucleate cells, which then encyst and divide into a brood of four.
Bibliography.—F. Cienkowski in Archiv für mikroskopische Anatomie (1865); Haeckel, “Die Moneren,” in Jenaische Zeitschr. (1868), vol. iv.; W. Zopf, “ Die Monadineen,” in Schenk's Handbuch der Botanik (1887), vol. iii. pt. ii., and Beiträge zur Physiologie und Morphologie niederer Organismen (1890); Delage and E. Hérouard, Traité de zoologie concrète, vol. i.; La Cellule et les protozoaires (1896); Marcus Hartog, Cambridge Natural History (1906), vol. i. (M. Ha.)