232 J. MCA. KATER. 



EXPLANATION OF PLATES. 



Figures I and 25 to 29 made from living material. Figures 2 to 24 made from 

 material fixed in hot Schaudinn's fluid and stained in hot iron-alum-haematoxylin, 

 counterstained with Bordeaux red. Figures 30 to 41 were made from specimens 

 fixed in Bouin's, stained in hot iron-alum-haematoxylin and counterstained with 

 either Bordeaux red or eosin. All drawings made with Abbe camera lucida. 

 Magnification 2500 X. 



PLATE I. 



FIG. i. Diagrammatic camera lucida drawing of living individual pressed 

 between two mold hyphae. cv, contractile vacuole; s, starch bodies. 



FIGS. 2, 3 AND 4. Showing extreme changes of shape. 



FIG. 5. Binucleate individual. 



FIG. 6. Resting nucleus. Extensive area of slightly chromatic cytoplasm 

 surrounding nucleus and filling posterior end. 



FIGS. 7 TO 24. Stages in the division of the nucleus and cell-body. 



Fig. 7. The transverse splitting of the karyosome, the first indication of 

 mitosis. 



FIGS. 8 TO ii. Continued fragmentation of the karyosome resulting in over 

 twenty chromatin particles imbedded in a chromatic cloud. Anchoring strands 

 persisting. 



FIG. 12. Nucleus becomes slightly elongate, anchoring strands disappear, and 

 seventeen or eighteen chromatin particles connected by slender achromatic strands 

 become visible. 



FIG. 13. The chromatin particles of the preceding one have paired to produce 

 the nine definitive chromosomes. An indication of a spindle appears and the poles 

 are lodged in centrioles which are connected by a paradesmose on the anterior side 

 of the nucleus. 



