STUDIES IN THE LIFE-HISTORY OF EUGLENA. 335 



Observations of the pairs of daughter animals in this quiescent 

 period immediately after separation shows interesting changes in 

 the relationship between the nucleus and the kinetic complex. 

 The deeply staining granule at the apex of the pear shaped 

 nucleus becomes surrounded by a lightly staining halo, increases 

 in size, and begins to show indications of breaking away from the 

 nuclear membrane (Fig. 15). In the meantime the nucleus begins 

 to rotate slightly and passes backward toward the posterior region 

 of the body. When this posterior migration begins the rhizoplast 

 connecting the granule with the blepharoplast, and in one of the 

 pair of daughter animals an intranuclear rhizoplast as well, can 

 usually be distinguished. As the animals begin to elongate after 

 the quiescent period the granule becomes disconnected entirely 

 from the nuclear membrane and passes with its surrounding halo 

 into the cytoplasm. The rhizoplasts may be seen for some time 

 after the separation but they eventually disappear and the granule 

 becomes entirely separated from the motor organs and the 

 nucleus (Figs. 16, 17). 



The separated granule seems to have no definite position in the 

 cytoplasm, but is found in various places. It remains as a 

 definite structure until the later stages of the next successive 

 division when it is observed to gradually fade out of view. In 

 some cases it has been observed as late as the quiescent period 

 after binary fission, so that two such bodies are then found in one 

 cell. These cases however, are exceptional. 



Behavior of Chromatophores During Mitosis. 



When the division process is first initiated in the animal, the 

 chromatophores are quite definitely delineated. A pyrenoid lies 

 in the center of each one and takes a fairly intense stain with the 

 haematoxylin. The body of the chromatophore stains with the 

 eosin rather than the haematoxylin. In material counter-stained 

 with Orange G the pyrenoids become a light orange yellow. In 

 Borrel's stain the body of the chromatophore becomes green while 

 the pyrenoid is blue. As the division process goes on the 

 pyrenoids show definite changes in contour and apparently in 

 composition. The chromatic substance becomes first aggregated 

 around the periphery in the form of distinct masses, which later 



