467 
must be really two individuals present, namely gametocytes of opposite 
sex, which have undergone cytoplasmic union and simulate a single 
parasite. 
Fig. 2. 
Figs. 1—8. Halteridium fringillae, from a chaffinch, showing double-nuclear para- 
sites. 7, chromatic grain (small nuclear element); p, pigment. >< 2000. 
Figs. 2, 3 and 6. Female forms. Figs. 5, 7 and 8. Male forms; the others uncertain. 
Fig. 9. Fig. 10. Fig. 11. 
Figs. 9—14. Halteridium fringillae. 
Figs. 9 and 10. Parasites showing a distinct split in the cytoplasm (e. s.). 
Figs. 11 and 12. Parasites in which one of the nuclei is male in character (m. .), the 
other female (f. ».): in the former a distinction in the cytoplasm of the two halves is 
also apparent. Fig. 13. Adult female gametocyte. Fig. 14. Adult male gametocyte. 
30* 
