EXPLANATION OF PLATES 



All figures of Giardia microti, Kofoid and Christiansen, draAvn with camera 

 lucida from smear preparations as described in pa^^er. Magnification X 2,750. 

 Full length of flagella not shown in many figures. 



PLATE 1 



Fig. 1. Ventral view, trophozoite in resting stage; note basal granules of 

 anterolateral flagella and the axostyle as a single rod. 



Fig. 2. Ventral view showing elongated karyosome and linin extension; 

 basal granules for caudal flagella. 



Fig. 3. Ventral view, prophase — knot-like spireme, and split in right 

 nucleus — stage previous to segmentation of spireme bands to form tetraploid 

 number of chromosomes. Parabasal; bacterial inclusions. 



Fig. 4. Ventral view, prophase — spireme of two strands; contraction of 

 chromatin to form chromosomes, axostyle partially split, parabasal body. 



Fig. 5. Ventral view, prophase — precocious splitting to form eight chromo- 

 somes or tetraploid number. In left nucleus separation of chromosomes to 

 show possible ancestral origin. Linin fibrils between chromosomes ; paradesmose. 



Fig. 6. Ventral view, prophase — precocious splitting of double spireme 

 band of each nucleus, forming tetraploid number of chromosomes, paradesmose 



Fig. 7. Ventral view, prophase — four chromatinic masses resulting from 

 fusion of the tetraploid number by pairs and their consequent contraction into 

 single mass; centrosome divided; axostyle partially divided; basal granules. 



Fig. 8. Lateroventral view, late prophase — four contracted chromatinic 

 masses at the equator. 



Fig. 9. Ventral view, metai^hase — equatorial plate in right nucleus; eight 

 chromosomes. Axostyle divided, blepharoplasts divided and formation of new 

 anterolateral flagella as far forward as chiasma. Eight nucleus in prophase. 



Fig. 10. Ventral view, late anaphase or early telophase — chromosomes 

 fused at poles. Nuclear membrane constricting. Axostyle almost completely 

 split. 



Fig. 11. Ventral view, telophase completed — four nuclei; small parabasal. 



Fig. 12. Dorsal or ventral view, "single individual" cyst — large para- 

 basals with connectives to axostyle. 



Fig. 1.3. Lateral view, so-called ' ' copulation ' ' cyst, but in reality the end- 

 result of binary fission. New organelles differentiating. 



Fig. 14. Dorsal or ventral view, "multinucleate" cyst — sixteen nuclei; 

 remains of two neuromotor apparatuses; parabasals. 



Fig. 15. Ventral view, binary fission — axostyles partially split; anterior 

 peristomal fibres of lower individual faint because of body being turned back- 

 ward. Bacterial inclusions. 



Fig. 16. Dorsal or ventral view, "binary fission" cyst — four nuclei; two 

 sets of neuromotor apparatuses. 



Fig. 17. Ventral view, metaphase — new anterolateral flagella as far as 

 chiasma; splitting of posterolateral flagella; equatorial plate formation. 



[26] 



