370 
The Schizogregarines 
and which consequently are not counted among the pathogenic Protozoa. 
The study of the life-histories of these relatively harmless organisms, in 
addition to being most interesting, may, however, throw light upon the 
biology of pathogenic forms. Among the former may be reckoned the 
Schizogregarines, a group of organisms of diverse external form, which 
are united by one special feature connected with their reproduction, 
namely, the intercalation in their life-cycle of an asexual method of 
multiplication. This feature serves to distinguish them from the 
common Gregarines, in which sexual reproduction alone obtains. The 
Schizogregarines have recently been the subject of several important 
papers by a small number of protozoologists. 
The object of the present review is to draw wider attention to this 
very interesting group, and to put forward suggestions—more especially 
in relation to their classification. Having personally worked at the 
group, on the Selenidiidae, and being acquainted at first hand with 
Siedleckia, Aggregata and Merogregarina, I feel that the time has 
arrived when a review of the group will prove useful, especially since 
the literature relating thereto is both widely scattered and difficult to 
interpret. 
A Glossary of Terms (see Appendix, p. 411) has been added for the 
general reader, at the request of the Editors. 
II. Historical Survey. 
The term “ Schizogregarine ” dates from the year 1900, when it was 
introduced by Leger. Parasites belonging to the sub-order Schizogre- 
garinae were known, however, before this date, for Aime Schneider 
described the first of these forms, Ophryocystis buetschlii in a pre¬ 
liminary note (1883), and subsequently (1884) gave fuller details 
regarding it. The body of this parasite, which occurs in the Malpighian 
tubules of a beetle, is irregular in shape and possesses pseudopodium¬ 
like processes (Fig. 4). Schneider was doubtful as to the position 
which should be assigned to these parasites, and, on account of the 
somewhat peculiar feature just mentioned, which he considered dia¬ 
gnostic, he called them the Amoebosporidia. As such they are described 
in the works of Wasielewski (1896), and Labbe (1899) on the Sporozoa, 
being placed in the appendices 1 as a separate and problematic order 
1 The supposed parasite of cancer was once referred to the problematic group Amoe¬ 
bosporidia (see Minchin, 1903, p. 191) and that of variola and vaccinia was in 1895 placed 
in a genus Amoebosporidium by L. Pfeiffer. 
