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J. MCA. KATER. 



spherical form is lost and they assume various shapes. In most 

 cases they entirely disappear before excystment. 



When the metachromatic granules are distributed through the 

 entire cell with only small dots of cytoplasm visible, acid dyes, 

 such as Bordeaux Red and eosin, have no effect on what cyto- 

 plasm can be seen, even when extra high percentages are used. 

 With the migration of the granules to the periphery the cytoplasm 

 regains its affinity for acid dyes. 



After the metachromatic granules have left the immediate 

 vicinity of the nucleus and the cytoplasm has become quite clear 

 we get the first indication of a new centriole and basal granule, in 

 the form of a thickening at the base of one of the anchoring 

 strands. This thickening next appears as a chromatic ball on the 

 strand, a part of which can be seen on each side of the ball. 

 Later it continues to the outside of the nuclear membrane. The 

 basiphilic material that has been drawn out of the karyosome 

 leaves the latter body without disfiguring it. Thus we see that 

 the centriole and basal granules are not formed from a slice of the 

 karyosome, but are taken from that structure by some definitely 

 organized scheme. The body on the outside of the nuclear 

 membrane divides, leaving one portion, supposedly the centriole, 

 while the other portion migrates out through the cytoplasm, 

 spinning a rhizoplast between it and the centriole. Before 



TEXT FIGURE A. Diagrammatic representation of stages in excystment and 

 the activity of a newly excysted individual. Arrows indicate direction of movement. 



