PLATE 8 



Giardia muris (Grassi) and G. microti Kofoid and Christiansen. X 2720. 

 All figures from smear preparations. 



Fig. 50. Giardia mtiris in prophase, nuclei with eight chromatin masses, ab- 

 normal condition in anterior halo in cytoplasm. From culture mouse. 



Fig. 51. Optical projection of G. muris from anterior end. Note ventral 

 location of anterolateral flagella (intraeytoplasmic part) and peristome, and 

 halo about axostyles and parabasals. From culture mouse. 



Fig. 52. Dorsal view of late anaphase in G. muris showing spindle fibers 

 between diverging chromosomes. From culture mouse. 



Fig. 53. Lateral view of G. muris showing a fiber passing from each para- 

 basal to dorsal side of the axostyles and a problematical faintly granular line, 

 found only in this preparation, passing from parabasal region towards the 

 blepharoplast. From culture mouse. 



Fig. 54. Lateral view of G. muris in situ on detached epithelial cells of 

 intestinal wall of host. From culture mouse. 



Fig. 55. Two free individuals of G. microti in end-to-end position similar to 

 that found in so-called conjugation cysts. From Microtus. 



Fig. 56. G. muris in late prophase showing the two parabasal bodies with 

 chromatic fibers passing to the dorsal side of the axostyle. From culture mouse. 



Fig. 57. G. microti in late prophase of binary fission with large karyosome, 

 divided blepharoplasts and dividing axostyle. Note slender parabasals. From 

 Microtus. 



Fig. 58. Later prophase of G. microti with split skein. From Microtus. 



Fig. 59. Metaphase of G. microti with blepharoplasts and anterior chiasma 

 divided, axostyle more deeply cleft, daughter centrosomes in polar positions, 

 four small chromosomes in equatorial plate in two distinct groups. From 

 Microtus. 



Fig. 60. Two free individuals of G. microti in end-to-end position, the upper 

 one (in figure) with the first division completed and cytoplasmic organelles 

 disintegrating, the lower is apparently in a late phase of total disintegration, 

 even the nuclei taking on a diffuse appearance. From Microt-us. 



Fig. 61. "Conjugation cyst" of G. microti with two normal individuals in 

 back-to-back position with ends reversed. From Microtus. 



Fig. 62. The same in a later phase. Each nucleus has completed one division. 

 In each "conjugant" there are two large nuclei with a large amount of 

 chromatin (possibly parents of gametic nuclei) and two smaller ones with less 

 chromatin (possibly first polar nuclei). From Microtus. 



Fig. 63. The same in a still later phase. The lower "conjugant" is still 

 in about the same phase as those in figure 62. The nuclei in the upper have all 

 divided again. The first polar nuclei have each given rise to two equal small 

 nuclei, and the other two each to one large nucleus with abundant chromatin in 

 four chromosomes (the possible gametic nucleus!) and one smaller one with 

 Ittle chromatin but still with apparently four chromosomes (second polar 

 nucleus?). From Microtus. 



Fig. 64. Cyst of G. microti with sixteen equal nuclei, two degenerating 

 axostyles and peristomes, the result of multiple fission. 



[54] 



