Rod-like bodies, probably of fungoid nature, are very common in Amoebae and Pelomyxa; see especially Gruber, Z. W. Z. xli. p. 210. The 'Glanz-korper' or 'glittering bodies' of P. palustris, are probably of parasitic origin (? Chytridian), and the source of the amoeboid and flagellate spores seen by Greeff, Korotneff, and Weldon (cf. Ray Lankester, Encycl. Brit., ed. ix., xix. p. 842). According to Leidy they are present in P. villosa, but Gruber did not observe them in that species, nor Korotneff in P. parvialveolata. Gruber found very similar bodies in Amoebae, particularly in A. quinta; see Z. W. Z. xli. pp. 191, 209. Butschli says he has seen spore-like bodies with membrane and nucleus, in Pelomyxa (palustrisl); see his Protozoa, Bronn's Thierreich, i, note, p. 159.
The nucleus is vesicular, i. e. provided with a membrane, nuclear fluid and chromatin. The modes in which the chromatin is arranged are very various, and in Amoebae, at any rate, have been asserted to characterise the species (Gruber). As to number, some Nuda and many Testacea are constantly uninucleate; Arcella and one Amoeba (A. binncleata) are typically binucleate; some Amoebae, Pelomyxa, Zonomyxa, invariably multinucleate; and in this case the number of nuclei may be constantly limited, e.g. to not more than eight in Amoeba tertia, or it may be indefinite and reach a high figure, e.g. some hundreds in A. quinta and Pelomyxa palus-tris. But both uni- and bi-nucleate forms may become multinucleate, e. g. Arcella, with 6, or even 40, Difflngia proteiformis with 40, and the increase is doubtless connected, as in Foraminifera, with reproduction.
1 The old question recurs, do these chlorophyl bodies belong to the organism, or are they symbiotic algae? Difflugia pyriform is and D. lobostoma are both stated by Leidy to be sometimes colourless, and other species of Difflugia may be occasionally green-coloured. The other five species named in the text are always green. When encystation takes place, the chlorophyl granules are included in the encysted mass. But attention may be drawn to fig. 12, PI. xxi, and figs. 8, 10, Pl. xxvi, of Leidy's monograph, where Hyalosphenia and Heleopera are respectively shown with tests empty save of scattered chlorophyl bodies. Two explanations only of this fact are possible, (1) that the chlorophyl bodies simply persist for a time after death, (2) that they are algae surviving as symbiotic algae do after the death of their host. The small size of the bodies in question forbids the supposition that they represent the contents of a cyst segmented. It may be noted that some Nuda have a great propensity to ingest green algae in quantity, e. g. the Amoeba binucleata of Gruber, Zonomyxa before its encystation.
2 Difflugia pyriformis perforates and sucks out by means of its pseudopodia the cells of Spirogyra; Stokes, Amer. Monthly Micr. Journal, iii. 1882, p. 93. So, too, a naked form (? Amoe-bine) described by Maupas, A. Z. Expt. ix. 1881, p. 358, and C. R. 89, 1879, p. 252.
Binary fission has been observed in some Nuda, and is probably universal among them. Among Testacea, in Pamphagus (=Lecythium) longitudinal fission takes place and includes the delicate test; similarly transverse fission in Diplophrys Archeri. But in those Testacea where the test is rigid, a process of modified fission or gemmation occurs, observed in all its details in Eaglypha alveolata by Gruber. A number of concavo-convex plates lay round the nucleus at the base of the test, which was entirely filled by protoplasm: the latter slowly protruded from the aperture of the test, and the loose plates passed by degrees up its sides out of its aperture, and arranged themselves on the surface of the swelling mass of protoplasm. As soon as this mass had attained the same size as the individual from which it was derived, the nucleus of the latter became greatly elongated, and its chromatin filaments arranged in parallel longitudinal lines; it then underwent fission, and one part passed into the new individual.
When the transfer was completed, lively currents in the protoplasm were set up in and between the two Eaglyphae. On their cessation the protoplasm was somewhat retracted from the walls of the tests, pseudopodia were extruded at the line of junction between their apertures, and then came separation. A similar process was observed, incompletely however, in Cyphoderia. From the fact that tests are often seen in apposition by their mouths, that loose plates have been seen within empty tests, e. g. in Quadrtda, Gruber believes that the process, as witnessed in Euglypha, is general among Testacea, the material of the new test, whether plates, chjtinous prisms or foreign bodies, being furnished by the parent. Individuals of Arcella are frequently seen in apposition, the shell of one being colourless, or nearly so, indicating its newness. But it is possible that in Arcella, and certain that in Platoum stercoreum, the new test covering the protoplasmic protrusion is formed by the protrusion itself. Whether conjugation ever really occurs is doubtful; but individuals of Arcella and of Difflugia glohdosa, with tests evidently old, have been found united aperture to aperture.
And in the first-named the production by gemmation (?) within the test of amoeboid young, with nucleus and contractile vacuole, and their subsequent escape, has been seen to follow this union (Biitschli). Similar amoeboid bodies, produced by gemmation or repeated fission in Arcella, have been traced until they acquired the characteristic test (Buck, Cattaneo). Conjugation of Amoebae has been said to occur1.
The formation of colonies, similar to those of Microgromia (p. 892, ante), takes place in a few instances. In Pamphagus ( - Lecythium) the individuals formed by fission may remain united by a protoplasmic mass from which radiate pseudopodia; or free individuals may fuse, two or more together (=.Gromia socialis, F. E. Schulze). Platoum stercoreum emits from the aperture of the test a mass of protoplasm, which acquires a test itself; new individuals then bud from the bridge uniting the two. So too in the Plectophrys of Entz. The colonies (= Cystophrys octdea) of Diplo-phrys Archeri are probably produced by fission. Encystation is general. In Amoebae stalked brown resting cysts and delicate digestive cysts have been recorded. Cochliopodium bilimbosum forms a thick cyst with outer gelatinous layer. Diplophrys Archeri has a double cyst, an inner smooth membrane, and an outer tuberculate. The Testacea, as a rule, encyst within the test, the aperture of which either collapses (Placocista) or is closed by a diaphragm, sometimes laminated, sometimes containing foreign bodies, e. g. diatom-frustules, algal cells, residues of food, etc. The organism itself contracts, and may have a single-walled cyst or a double, both forms occurring in the same species.