EXPLANATION OF PLATES 



All figures of Giardia muris (Grassi) drawn with camera lucida from smear 

 preparations fixed in warm Schaudinn's fluid and stained in Heidenhain's iron 

 haematoxylin, unless otherwise stated. X 2720. All from culture mice unless 

 otherwise stated. Full length of flagella not shown in any figures. 



PLATE .5 

 Figures 1-6, 8-15 are of Giardia muris (Grassi). 

 Figure 7 is of Giardia microti Kofoid and Christiansen. 



Fig. 1. Dorsal view, trophozoite with quiescent nucleus, ventral cytostome 

 coincident with posterior peristome. 



Fig. 2. Dorsal view, the same, ventral cytostome extended posteriorly 

 beyond posterior peristome. 



Fig. 3. Dorsal view, first indications of division, nuclear membrane heavily 

 incrusted, intranuclear rhizoplast has disappeared, axostyle widening, body 

 rounded up. 



Fig. 4. Dorsal view, early prophase, peristome contracted, or unusually 

 small, nucleus rounded up, filled with intranuclear chromidial cloud, karyosome 

 halo distinct, parabasals enlarged, cytoplasmic chromidia abundant. Note 

 chromatic intracytoplasmic part of postero-lateral flagella. 



Fig. 5. Lateral view of trophozoite showing dorsal position of parabasals 

 in the dorsal hump and ventral position of blepharoplasts, of anterior and pos- 

 terior peristome, and of the intracytoplasmic parts of the lateral flagella. 



Fig. 6. Dorsal view of early prophase. Body rounded up, nuclear membrane 

 faint, intranuclear cloud present, blepharoi)last, anterior chiasma, axostyle, pos- 

 terior axostylar granule, posterior chromatic lines, and posterior lateral flagella 

 ilivided. Karyosome enlarged, intranuclear chromidia disappearing, centrosomes 

 dividing(?). 



Fig. 7. Early prophase, blepharoplasts dividing, anterior peristome and 

 intracytoplasmic part of antero-lateral flagella very distinct, centrosomes 

 divided (?), somewhat abnormal. 



Fig. 8. Late jirophase, axostyle dividing, blepharoplasts divided, centro- 

 somes divided, in polar position, with paradesmose between on the outside of 

 the nuclear membrane, karyosome breaking up. 



Fig. 9. Ventral view of late prophase, blepharoplasts divided, axostyle in 

 division, no flagella divided. Nuclear membrane encrusted, eight chromatin 

 granules in nucleus. 



Fig. 10. Dorsal view of a later stage of prophase, axostyle and posterior 

 flagella completely divided. 



Fig. 11. The same of similar stage, blepharoplasts only divided, the eight 

 chromatin granules arranged in two rows of four each. From Peromyscu: 



Fig. 12. The same, of similar stage, chromatin in two parallel granular 

 masses, chiasma and blepharoplast divided, axostyle in division, ventral flagella 

 thrown forward. From Peromyscus. 



Fig. 13. Dorsal view of late projihase, blepharoplasts and axostyle divided. 

 Chromatin in two sinuous finely granular, subparallel masses. 



Fig. 14. Dorsal view of similar stage, blepharoplasts and chiasma, axostyle 

 dividing, chromatin in four masses, peristome thickened. 



Fig. 15. Dorsal view of similar stage, blepharoplasts and axostyle divided. 

 Posterior peristome faded out. From Perovxyscus. 



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