1919] Kofoid-Swczy: Trichonymplta campanula 63 



As the two parts of the centroblepharoplast separate, the alveoli 

 frequently form a rosette at the base of each (pi. 8, fig. 38 ; pi. 9, 

 fig. 42), presenting, especially in a focus showing the oblique fibers, 

 striking resemblances to well developed asters in optical section. 

 With the further separation, the angle formed by the splitting ecto- 

 plasmic structures becomes greater and extends farther out towards 

 the periphery of the ectoplasmic region (pi. 8, fig. 38). This region 

 is usually conspicuous since the flagclla as well as surface ridges, 

 myonemes and alveoli have been drawn aside, leaving only the granu- 

 lar endoplasm beneath the thin ectoplasmic layer. The paradesmose 

 becomes thicker and broader, generally forming a heavy band that 

 persists throughout the entire process of division, and may oeeasion- 

 allj' be found for some time after the final separation of the daughter 

 nuclei (pi. 11, fig. 75). 



No other changes in the ectoplasmic structvires during these stages 

 have been detected. The staining reactions of the neuromotor appa- 

 ratus seem to vary slightlj^ as the different phases follow each other. 

 At the beginning of its division it often pi'esents a greater affinity for 

 iron haematoxylin than during the later phases. This, however, may 

 possibly be due to changes in the preparation of the material, as 

 decolorization of slides containing mitotic figures was carried on with 

 the view of obtaining the best possible results for the chromosomes, 

 without regard to the remainder of the cell. 



In the final stages of division, when the complete separation of the 

 divided organelles has taken place, an enveloping movement of the 

 ectoplasmic zone may be seen. This begins with a gradual creeping 

 out of the margins of the divided area (pi. 12, fig. 76), partly as a 

 result of the spreading of structures already formed and partly as 

 new outgrowths over the undifferentiated intermediate zones. As 

 the two daughter organisms separate, pulling out a long protoplasmic 

 bridge between them, the rounding-up of the body which results aids 

 in closing the gap between the margins of ectoplasm (pi. 12, fig. 79). 

 This process may, however, be hastened or retarded in some indi- 

 viduals, and is not always synchronous in the two daughter organisms. 

 This possibly results from contractions of the intermediate zones or 

 of the old differentiated zones. In plate 12, figure 85, an almost 

 complete union of the borders of the ectoplasm has taken place in one 

 individual of the dividing body, while the other still shows a rather 

 broad gap between the margins of ectoplasm. In figure 84 of the 

 same plate the final separation of the two daughter organisms has 



