Phylum Protoplasta [ 193 



Doflein. Organisms bearing at the same time flagella and typical axopodia. Dimor- 

 pha, free-swimming, with two unequal flagella. Actinomonas, Pteridomonas, Cilio- 

 phrys, with one flagellum, either free-swimming or attached by a protoplasmic stalk. 

 Family 6. Actinophryida [Actinophryidae] Glaus 1874. Askeleta Hertwig and 

 Lesser in Arch. mikr. Anat. 10 Suppl. 164. (1874). Aphrothoraca seu Actinophryidae 

 Hertwig Org. Radiolar. 142 (1879). Order Aphrothoraca Butschli (1881). Suborder 

 Aphrothoraca Minchin (1912). Family Camptonematidae Poche in Arch. Prot. 30: 

 187 (1913). Cells typically spherical, with typical axopodia, having no flagella nor 

 shells nor skeletons. Actinophrys Sol Ehrenberg and Actinosphaerium Eichhornii 

 (Ehrenberg) Stein are common in fresh water among algae, living as predators 

 largely on diatoms; Actinophrys is uninucleate, the cells to 50^ in diameter; Actono- 

 spaerium is multinucleate, the cells to lOOOjl in diameter. Camptonema is marine. 



Mitosis in Actinophrys as described by Schaudinn (1896) occurs within an intact 

 nuclear membrane which undergoes constriction; the dividing nucleus lies within a 

 spindle-like body of cytoplasm. Schaudinn and Belar (1923) observed conjugation. 

 Pairs of gametes, which are usually sister cells but may sometimes be random pairs, 

 lie within a cyst wall of secreted material. The nucleus of each gamete undergoes 

 meiosis; at the end of each meiotic division, one of the daughter nuclei is digested; 

 thus each gamete comes to possess a single haploid nucleus. Syngamy and karyogamy 

 follow in due course and the zygote becomes walled. An old account of the cytology 

 of Actinosphaerium by Hertwig is defaced by descriptions of the origin of nuclei from 

 fragments of nuclei (chromidia), and of nuclear fusions at two separate stages of 

 development. 



Family 7. Heterophryida [Heterophryidae] Poche in Arch. Pr«it. 30: 189 (1913). 

 Heliozoa Chtamydophora Archer in Quart. Jour. Micr. Sci. n.s. 16: 348 (1876). 

 Order Chlamydophora Butschli (1882). Suborder Chlamydophora Minchin (1912). 

 Family Lithocollidae Poche I.e. The cells or their main bodies spherical with axopodia 

 projecting through a gelatinous envelope. Heterophrys and Astrodisculus are simply 

 globular cells. Elaeorhanis and Lithocolla are similar but with grains of sand or dia- 

 tom shells imbedded in the envelope. Actinolophus is stalked. Sphaerastrum becomes 

 colonial by incomplete division of the cells. 



Family 8. Acanthocystida [Acanthocystidae] Glaus 1874. Chalarothoraca Hert- 

 wig and Lesser in Arch. mikr. Anat. 10 Suppl. 193 ( 1874). Chalarothoraca seu Acan- 

 thocystidae Hertwig Org. Radiolar. 142. (1879). Order Chalarothoraca Butschli in 

 Bronn Kl. u. Ord. Thierreichs 1: 325 (1882). Suborder Chalarothoraca Minchin 

 (1912). Resembling the preceding family, but the gelatinous envelope containing 

 hard bodies, supposedly usually siliceous, of definite form. In Raphidophrys, these 

 bodies are curved needles; in Pinacocystis, small plates; in Acanthocystis and Pinacio- 

 phora, disks bearing a central spine which is in some species forked. The cell of Wag- 

 nerella (a marine form, on rocks in bays) consists of a globular head with spines and 

 axopodia, borne on a protoplasmic stalk attached by a foot; the nucleus lies in the foot. 

 In these forms the axial filaments of the pseudopodia radiate from a central gran- 

 ule located outside the nucleus (in Wagnerella, in the head). Schaudinn (1896) re- 

 ported nuclear division in Acanthocystis as being either amitotic or mitotic: the 

 report of amitosis is of course not to be taken seriously. In the mitotic process, the 

 central granule acts as a centrosome; the chromosomes are numerous and minute; 

 the nuclear membrane disappears during the middle stages. Nuclear division may be 

 followed by division of the cell into two, or may be repeated and followed by produc- 

 tion of buds. The buds may lose their pseudopodia and develop paired flagella. It is 



