The chlorophyl of the Algae is partly dissolved and changed, colouring the protoplasm red, rosy, orange, yellow, or brown. V. polyblasta feeds on Euglenae. The Amoeba is large, more or less Actinophrys-Yike, but of irregular shape, with pointed pseudopodia except in V. pedata1, which moves by a one-sided hyaline border. It is uni-nucleate. Binary fission has been observed as well as the fusion of 2-4 Amoebae into plasmodia in V. variabilis and V. polyblasta. The plasmodia may divide, and in V. polyblasta pass into a resting or hypnotic phase. The cysts may have one, two, or several membranes. The zoocyst, which is very irregular in shape in V. variabilis, in V. pendula attached to its host by a peduncle, and in V. pedata by a plug or process projecting into the cell it has just plundered, gives origin to 2-4 amoebulae which escape simultaneously at as many different spots, leaving faecal residues behind as brown balls. The sporocyst contains a single resting-spore except in V. variabilis where there are two or more. The resting-spore contracts successively several times, forming a cyst membrane at each contraction 2. The Monodopsis Vampyrel-loides of Klein is probably a Vampyrella. One or more of its Amoebae surround a Tetraspora, fuse and encyst.
The contents of the cyst divide into 2-3 amoebulae. Leptophrys (Vampyrella) vorax is large, sometimes colourless, sometimes reddened by digested chlorophyl, multi-nucleate, filled with paramylum bodies, often mistaken for vacuoles. In locomotion it pushes out irregular lobes and its pseudopodia, which spring from the lobes, are fine and pointed. It undergoes fission, and forms fusion-plasmodia. The zoocyst is of irregular shape and gives origin to 2-6 amoebulae. The sporocyst is globular or elongate with a thin membrane, and all in-gesta are expelled before its formation. Its contents contract, and may form a second membrane and contract again; they are enveloped in a tough spore-membrane. Endyomena polymorpha is a uni- or multi-nucleate amoeba of variable size and irregular shape, living within the sheaths of Scytonemeae. The cyst (? zoocyst) is globular or irregular in shape; its contents form a second cyst-membrane.
The second family of M. azoosporeae is the Bursullineae. It contains only Bursulla crystallina which lives on horse-dung. The Amoeba has long pointed pseudopodia. Two or more Amoebae fuse into a rose-red plasmodium. The latter gives origin to one, or if large to 2-3 zoocysts, which are globular or oval and pedunculate. The contents divide into eight Amoebae; the apex of the cyst then gelatinises and suffers them to escape. The resting-spore (? phase) is globular with a thick membrane: the latter bursts and its contents give rise to a zoocyst.
The third family is the Monocystaceae, which contains aquatic genera of voracious habit and giving rise only to a sporocyst3. Zopf places here Myxastrum (p. 916, ante). The other member is Enteromyxa paludosa which feeds on Oscilla-toriae and Diatoms, the former tinging the protoplasm blue-green. The Amoeba is typically long (1/2-1 mm.) and worm-like; it may become branched or reticulate.
1 ? = Hyalodiscus = Plakopus, p. 905 and note, ante.
8 Leidy in his 'Freshwater Rhizopoda of N. America ' speaks, p. 255, with reference to Vampyrella lateritia (= Spirogyrae) of the rapid emission and withdrawal of pin-like pseudopodia, consisting of a short stalk with a head. As he himself points out (p. 256), other observers (Cienkowski, Hertwig, and Lesser) have noticed rapid shooting out and as rapid withdrawal of granules in the pointed or lobose pseudopodia of this species. It may be noted here that Zopf states that the membrane of the zoocysts of Vampyrella pedata, Monodopsis Vampyrelloides, and Leptophrys vorax, yield with Iodine and Sulphuric acid the blue colour characteristic of cellulose.
3 Zopf speaks in his article in the Encyclopaedic, etc, quoted infra, of plasmodia in Myxastrum and Enteromorpha. But in neither of these genera has the formation of a plasmodium been actually observed. Both organisms are of large size, Myxastrum fa in., Enteromyxa fa-fa in.
At first it emits numerous cylindrical hyaline pseudopodia, in later stages short broad processes, by which it gathers its food. When it encysts, it secretes a thin membrane, contracts, especially in breadth, and is by degrees segmented into a number of rounded portions. Each portion becomes multangular, secretes a tough membrane and breaks up into two or several, rarely many, resting-spores. The latter are ellipsoidal or bean-shaped with a membrane. The sporocyst is frequently violet in colour.
There remain a few amoeboid forms not included in the above described groups. Boderia is marine, 1/16-1/4 inch in size, orange or brown in colour, of varying shape, with a membranous investment (?) from openings in which protrude 3-4, sometimes more, long and branched pseudopodia with granule streaming. It has one or more nuclei (?). Gymnophrys cometa is non-nucleate, marine and freshwater, naked, colourless, with a few branched and anastomosing pseudopodia displaying granule streaming. Biomyxa vagans is also marine and freshwater. It is amoeboid and passes through most varied changes of form, from a Heliozoon-like aspect to a network. It has minute contractile vacuoles, and many nuclei. Protamoeba is non-nucleate, with pseudopodia not branched nor anastomosing, varying in shape but constant in different species; of variable size, multiplying by fission. Its different species are found in either fresh or salt water. The freshwater Gloidium closely resembles a Protamoeba. It has lobose pseudopodia, a contractile vacuole, and divides simultaneously into four parts while in a mobile condition. It surrounds itself sometimes with a laminated cyst. Protogenes is marine, non-nucleate, globular or irregular in shape, with fine branched and anastomosing pseudopodia.
Binary fission has been observed. Arachnula impatiens is a fresh or brackish water form, rapid in motion, non-nucleate, with contractile vacuoles, the pseudopodia a little branched, sometimes anastomosing, generally originating from lobes which appear at any part of the body. The latter is usually drawn out into a narrow band. A transparent cyst has been observed. The Monopodium of Mereschkowski appears to be identical with the Aletiu??i of Trinchesi. It is marine, and found attached by a pseudopodium to the algal Chaetomorpha or Lepto-thrix (Zingbya) and is characterised by its mode of locomotion. It throws out a long pseudopodium which attaches itself to another algal filament and then draws the body onwards, releasing afterwards the original pseudopodium of attachment. Trinchesi describes Aletium at rest as pyriform, 3 mm. long, yellow in colour, feeding on the Chaetomorpha, and giving off branched pseudopodia. He observed it resolved into a number of globular bodies held together by a colourless mass and in one instance showing amoeboid motions. Mereschkowski witnessed the fusion of two individuals, the resulting mass breaking up into three. Protobathybius is the name given by Bessels to large masses of free protoplasm dredged in Smith's Sound at a depth of 92 fathoms.