120 



BIOLOGY OF THE PROTOZOA 



aster consisting of centrosomes, centrodesmose and astral rays made 

 up of the radiating fibrils (Fig. 50, p. 95 — see also Trichonympha cam- 

 panula) . Stern (1914) , however, found that mitotic spindles may arise 

 in Acanthocystis without any connection with the central granule (Fig. 

 67) . The central grain, however, takes no part in reproduction by bud- 

 ding, whereby ameboid or flagellated buds are formed which contain 

 a nucleus derived from the parent cell nucleus, but no central grain. 

 This nucleus, however, contains an endobasal body which divides 

 and one of the daughter granules emerges from the nucleus as it 

 does in Dimastigamoeba gruberi (p. 34), but retains its eentrodes- 

 mose for some time and ultimately forms the central grain of the 



Fig. 66. — Relation of axial filaments to nuclei. Section of Actinophrys sol with 

 axial filaments arising from intranuclear granules in recently divided nuclei. (After 

 Schaudinn.) 



adult organism (Schaudinn, 1896; Zuelzer, 1909; Acanthocystis acu- 

 leata, Wag nerd I a borealis, Fig. 50). Similarity with the centrobleph- 

 aroplast in flagellates is thus shown (1) by its origin from an 

 intranuclear centriole; (2) by its relation to axial filaments which are 

 homologous with rhizoplasts; (3) by its history during mitosis. The 

 analogy is further strengthened by its relation to the flagella and to 

 the axopodia which are simultaneously present in some of the Helio- 

 flagellida {Actinomonas mirabilis, Kent, Ciliophrys marina, Caullery, 

 and Dimorpha m titans, Gruber). In Dimorpha m utans (Fig. 13, p. 34), 

 the central grain lies near one pole of the cell where it forms the 

 basal body of the two flagella as well as the focal point for the axial 

 filaments; here flagella and axial filaments appear to be homologous 



