1080 PARASITES OF PROTOZOA 



genus is Metchnikovella CauUery and Mesnil, with thirteen species; 

 there are three species of Amphiamblys C. and M., three of Amphia- 

 cantha C. and M., and one of Caulleryella Dogiel. All the grega- 

 rines that have been found to contain these hyperparasites occur in 

 annelids, and all but one in marine polychaetes. This one, Metchnikovella 

 hessei Mesnil, 1908, is found in a monocystid gregarine of the terrestrial 

 oligochaete Friderkia polycheta. The parasitized gregarines belong to 

 various groups, and, according to Caullery and Mesnil (1919), there is 

 no parallelism between the structure of the Metchnikovellidae and that 

 of the gregarine hosts. The host-specificity is apparently on an ethological 

 rather than a phylogenetic basis. The species of A77iphiacantha, however, 

 have been found in gregarines of the genus Ophiodina [Lecudina) or 

 related forms in Lumhrkonereh in France and California. 



Caullery and Mesnil (1919) stated that when there is an infection, 

 the greater part of the gregarines of a host are invaded. Stubblefield 

 (MS) found a high frequency of Amphiacantha in about 20 percent 

 of the worms collected, almost all of which contained gregarines. 



Published literature gives little information about details of the life 

 cycles of Metchnikovellidae. Caullery and Mesnil (1919) regarded the 

 individualized, nucleated bodies enclosed by the cyst membrane as spores 

 ("germes sporaux"). When the cysts are ingested by an annelid, these 

 are released in the digestive tract, and penetrate into the cytoplasm of 

 the gregarines. Growth and nuclear division lead in some instances to 

 multinucleate plasmodia. In other instances there are numerous indi- 

 vidual, uninucleate bodies, isolated or arranged in series. Caullery and 

 Mesnil supposed that cysts develop by the formation of a membrane 

 around groups of these cells or the plasmodium. The cyst contents is 

 thus either multinucleate or in individualized uninucleate bodies from the 

 beginning. Such a manner of cyst formation is difficult to understand. 



Stubblefield (MS) prepared an account of the life cycle of Amphia- 

 cantha, which is in closer agreement with that of Haplosporidium. 

 He found evidence for the penetration of the gregarine by an active 

 sporozoite; the growth of the sporozoite, followed by schizogony, to 

 produce trophozoites; the development of the trophozoite into a cyst, 

 which is at first uninculate; nuclear and cytoplasmic division, to pro- 

 duce bodies in the cyst (Fig. 224), which he considered to be 

 gametocytes; the release of these by the rupture of the cyst within the 



