154 
ALBERT H. TUTTLE 
EXPLANATION OF FIGURES 
7 A stage not infrequently observed, in which the newly formed chromosomes 
are massed at the center of the nucleus : the nucleolus is still present. 
8 Gathering of the chromosomes at the equator with appearance of spindle 
fibers. In this figure, and those immediately following, only a portion of the 
chromosomes are represented, for the sake of greater clearness. The nucleolus 
has disappeared. 
9 Another and more frequent mode of assemblage of the chromosomes, 
showing the marked tendency to straggle. The spindle fibers are well developed 
at one pole only. The upturned end of a straggling chromosome might at the 
first glance be mistaken for a centrosome. 
10 Separation of the daughter chromosomes. 
11 Separation of the daughter chromosomes. The rounded masses shown 
in this and the following figures represent fragments that have become perma- 
nently detached from some of the chromosomes, and gradually assume the form 
shown. The loose appearance of the spindle is characteristic. 
12 Anaphase. The shaded body shown in the lower portion is a pyrenoid 
seen through the nucleus. 
