H. B. Fantham 
407 
placed in the Ectospora, along with the Eugregarinae, the Coccidiidea 
and the Haemosporidia. 
However, it does not seetn profitable to discuss further the 
classification of the Sporozoa, on the basis of the life-cycle of the 
Schizogregarines. Classification is at the best only tentative, and must 
change with advancing knowledge. It is of much more importance to 
work out further complete life-cycles, and so—by filling in the gaps—to 
increase our knowledge of the facts which must underlie all classifica¬ 
tion. 
X. Summary. 
1. The term Schizogregarinae Leger (1900) is the name now given 
to a sub-order of the Gregarinidct, the remaining members of which are 
known as the Eugregarinae. The Schizogregarines were formerly 
known as Amoebosporidia Aime Schneider (1884), a name given in 
misapprehension of the character of the cytoplasmic processes, fixative 
in function, present in the genus Ophryocystis. Two species of 
Ophryocystis (0. buetschlii and 0. francisci) were the only members of 
this sub-order known before 1900. 
2. At present the sub-order Schizogregarinae contains five families : 
Ophryocystidae, Scliizocystidae, Selenidiidae, Merogregarinidae, and 
Aggregatidae. 
3. All these organisms show well-marked schizogonic stages in 
their life-history, and—with the possible exception of the Aggregatidae — 
follow after the Eugregarinae in their methods of sporogony. 
4. In Ophryocystis and Schizocystis the schizogony is extracellular, 
that is, these forms are ectoschizous. The life-cycle of the former is 
shown in Fig. 1. In these parasites the number of the nuclei in the 
schizont increases simultaneously with its volume. 
5. In Selenidiuvi and Merogregarina the schizogony is intracellular, 
in other words these forms are endoschizous. The life-cycle of the 
former is illustrated in Fig. 3. In these forms the schizont is 
uninucleate during its growth, only becoming multinucleate at the end 
of the growing period. 
6. Ophryocystis forms only one sporocyst, a fact which has been 
emphasised by Leger and Duboscq (1908), by the placing of the 
Ophryocystidae in a special section, the Monospora. However, this 
apparent peculiarity is easily explained by a process of reduction and 
degeneration having taken place, affecting with one exception all the 
Parasitology i 26 
