EXPLANATION OF PLATE 



All figures are of cysts of Giardia microti from the meadow mouse and of the 

 cysts of Giardia found in the culture rats, drawn with camera lucida from smear 

 preparations. Magnification, X 2750. 



PLATE 1 



Fig. 1. Ventral view, single-individual cysts found in small intestine and 

 caecum; nuclei in resting stage. Two parabasals dividing. 



Fig. 2. Dorsal view, single-individual cyst found in caecum; nuclei divid- 

 ing, parabasals in division. 



Fig. 3. Dorsal view, single-individual cyst found in caecum of meadow 

 mouse; nuclei in anaphase, small parabasals, axostyle completely split. 



Fig. 4. Dorsal or ventral view, single-individual cyst, chromatin in one 

 nucleus divided into two masses. Parabasals dividing. Cyst from caecum 

 of meadow mouse. 



Fig. 5. Dorsoventral view, binary cyst from colon of meadow mouse; 

 nuclei divided, two parabasals. 



Fig. 6. Dorsoventral view, binary cyst from colon of meadow mouse; four 

 nuclei, new organelles, no parabasals. 



Fig. 7. Side view, binary cyst from colon of meadow mouse; shows plan 

 of cleavage of the parent body to form two daughter flagellates. No parabasals. 



Fig. 8. Side view, binary cyst from colon and rectum of meadow mouse. 

 Two complete individuals with their organelles, no parabasals. 



Fig. 9. Dorsoventral view, multinucleate cyst, two axostyles, large para- 

 basals, twelve nuclei. Found in small intestine of meadow mouse. 



Fig. 10. Dorsoventral view, multinucleate cyst, two axostyles, twelve 

 nuclei, parabasals. Found in small intestine of meadow mouse. 



Fig. 11. Dorsoventral view, multinucleate cyst from small intestine of 

 meadow mouse; two axostyles, no parabasals, sixteen nuclei. 



Fig. 12. Dorsal view, single-individual cyst from jejunum of rat; nuclei in 

 anaphase, large parabasals, axostyle partially split. 



Fig. 13. Dorsoventral view, binary cyst from jejunum of rat; four nuclei, 

 large parabasals. 



Fig. 14. Dorsoventral view, binary cyst from colon of rat; four nuclei and 

 three large parabasals. 



Fig. 15. Ventral view, binary cyst from jejunum of rat; four nuclei in 

 resting stage, parabasals. 



Fig. 16. Side view, binary cyst from jejunum of rat; four nuclei two exo- 

 styles, large parabasals. 



Many of the cysts in the preparations show a shrinkage away from the cyst 

 wall; this is attributed to plasmolysis at the time of fixation. 



[134] 



