270 HANDBOOK OF PROTOZOOLOGY 



Selenococcidium intermedium Leger and Duboscq (Fig. 110). 



Fig. 110 Selenococcidium intermedium. X550 (After Leger and Duboscq). 

 a, a schizont in the host gut; b, c, schizogony; d, microgametocyte; e, 

 microgametes; f, macrogametocyte; g, macrogamete; h, zygote or oocyst. 



Family 2 Aggregatidae Reichenow 



Genus Aggregata Frenzel. With alternation of generations 

 and of hosts. The zygote forms numerous spores, each con- 

 taining several sporozoites. 



Aggregata eherthi (Labbe) (Fig. 111). Schizogony in the 

 crab, Portnnus depurator, and sporogony in the cephalopod. 

 Sepia officinalis. The spore germinates in the digestive tract 

 of the crab {a, b), and the sporozoites undergo growth and 

 schizogony (during which six chromosomes are distinctly visi- 

 ble) in the peri-intestinal connective tissue cells (c, d). When 

 the crab is eaten by a cuttlefish, the merozoites penetrate the 

 gut wall {e) and there develop into micro- and macro-gameto- 

 cytes, and further into gametes. Anisogamy results in zygote- 

 formation (g). The nucleus of the zygote or oocyst shows 12 

 chromosomes which become divided into two groups of six at 

 the first nuclear division (Dobell, Belaf) {h). Each of these 

 two nuclei undergoes mitotic division repeatedly and produce 

 numerous sporoblasts (i) and finally spores (a). Each spore 

 contains three sporozoites and a residual mass. Several other 

 species have been observed in the same groups of the hosts. 



Genus Caryotropha Siedlecki. Oocysts develop numerous 

 spores, each with many sporozoites. 



