376 



KOFOID AND SWEZY. 



PLATE 7. 



Binary fission in Eutrichomaslix serpentis (Dobell). X 2175. All from 

 Crotalus oregonus Holbrook except Figures 81, 84, 86-88, 90, 91, and 95 which 

 are from Pituophis catenifer Baird and Girard. 



FiGrRE 79. Free-swimming trophozoite. Xote three anterior and one 

 trailing posterior flagellum, arising from anterior blepharo- 

 plast, cytostome, axostyle, and nucleus with central karyosome. 



Figure 80. Trophozoite in posterior blob formation or plasmectomy. 



Figure 81. Trophozoite rounding up prior to fission. Nucleus with numer- 

 ous karyosomes (skein formation?). 



Figure 82. Late prophase. Daughter blepharoplasts migrating apart with 

 paradesmose between; two flageUa with each blepharoplast; 

 four chromosomes in the nucleus. 



Figure 83. Later stage showing extranuclear spindle fibers running from 

 blepharoplasts to spheroidal nucleus. 



Figure 84. Nucleus fusiform; two cytostomes present. 



Figure 85. Metaphase approaching; chromosomes in equatorial plate; 

 slight chromidial cloud about anterior end of vanishing 

 axostyle. 



Figure 86. The same. Note difference in shape of chromosomes. 



Figure 87. Metaphase. Chromosomes beginning to divide by transverse 

 constriction. 



Figure 88. Division nearly completed. Note small lagging chromosome. 



Figure 89. Early anaphase. 



Figure 90. Early telophase. Constriction of nuclear membrane, massing 

 of chromosomes; paradesmose persisting; new flageUa grow- 

 ing out. 



Figure 91. Telophase. Nuclei separated; full complement of flagella 

 present; paradesmose stiU present. 



Figure 92. Telophase. Chromosomes connected with blepharoplast bj' 

 chromatic threads; paradesmose disappeared; one axostyle 

 present. 



Figure 93. Paradesmose stretched taut by diverging nuclei; two axostyles 

 and two cytostomes present. 



Figure 94. Two daughter cells parting, with slender plasmadesmose con- 

 necting them. 



