LABYRINTHULIDEA  , the name given by

Sir Ray Lankester (1885) to Sarcodina (q.v.) forming a reticulate plasmodium, the denser masses united by fine pseudopodical threads, hardly distinct from some Proteomyxa, such as Archerina . This is a small and heterogeneous group . Labyrinthula, discovered by L . Cienkowsky, forms a network of relatively stiff threads on which are scattered large spindle-shaped enlargements, each representing an amoeba, with a single nucleus . The threads are pseudopods, very slowly emitted and withdrawn . The amoebae multiply by fission in the active state . The nearestapproach to a " reproductive " state is the approximation of the amoebae, and their separate encystment in an irregular heap, Labyrinthulidea . several cells which have lost their definite spindle-shaped contour. s, Corpuscles which have become spherical and are no longer moving (perhaps about to be encysted) . 4 . A single spindle cell and threads of Labyrinthula macrocystis, Cienk. n, Nucleus . 5 . A group of encysted cells of L .

Macrocystis, embedded in a tough secretion . 6, 7 . Encysted cells of L. macrocystis, with enclosed

protoplasm divided into four spores . 8, 9 . Transverse division of a nonencysted spindle-cell of L. macrocystis . i . A colony or " cell-heap " of Labyrinthula vitellina, Cienk., crawling upon an Alga . 2 . A colony or " cell-heap " of Chlamydomyxa labyrinthuloides, Archer, with fully expanded network of threads on which the oat-shaped corpuscles (cells) are moving. o, Is an ingested food particle ; at c a portion of the general protoplasm has detached it-self and become encysted . 3 A portion of the network of Labyrinthula vitellina, Cienk., more highly magnified. p, Protoplasmic mass apparently produced by fusion of several filaments. p', Fusion of recalling the Acrasieae . From each cyst ultimately emerges a ~ and for other personal adornments . Lac is a principal ingredient single amoebae, or more rarely four (figs .

6, 7) . The saprophyte Diplophrys (?) stercorea (Cienk.) appears closely allied to this . Chlamydomyxa (W . Archer) resembles Labyrinthula in its freely branched plasmodium, but contains yellowish chromatophores, and

minute oval vesicles (" physodes ") filled with a substance allied to tannin—possibly phloroglucin—which glide along the plasmodial tracks . The cell-body contains numerous nuclei; but in its active state is not resolvable into distinct oval amoeboids . It is amphitrophic, ingesting and digesting other Protista, as well as " assimilating" by its chromatophores, the product being oil, not starch . The whole body may form a laminated cellulose resting cyst, from which it may only temporarily emerge (fig . 2), or it may undergo resolution into nucleate cells which then encyst, and become multinucleate before rupturing the cyst afresh . Leydenia (F . Schaudinn) is a parasite in malignant diseases of the pleura . The pseudopodia of adjoining cells unite to form a network; but its affinities seem to such social naked Foraminifera as Mikrogromia . See Cienkowsky, Archiv f .

Microscopische Anatomie, 274 (1867), xii . 44 (1876); W . Archer, Quart . Jour . Microscopic

Science, xv . 107 (1875); E . R . Lankester, Ibid., xxxix., 233 (1896); Hieronymus and Jenkinson, Ibid., xlii . 89 (1899); W . Zopf, Beitrage zur Physiologie and Morphologie niederer Organismen, ii . 36 (1892), iv . 6o (1894) ; Permed, Archiv fur Protistenkunde, iv .

296 (1904); F . Schaudinn and

Leyden, Sitzungsberichte der Koniglich preussischen Akademie der Wissenschaft, vi . (1896) .