1906] YAMANOUCHI—POLYSIPHONIA VIOLACEA 405 
of the nuclear cavity, and the spindle. As regards the centers of 
kinoplasmic activity, in the preceding stage the kinoplasm is shown 
in the process of accumulation at the two poles, and a single clearly 
differentiated granule may be interpreted as the first visible indication 
of approaching spindle formation. At the time when the equatorial 
plate is formed, the kinoplasmic material becomes massed more 
densely than before, and two very large centrosphere-like structures 
are differentiated at the poles of the spindle (jigs. 5,6). These 
kinoplasmic bodies have a compact, well-defined form, but are with- 
out radiation. The nuclear cavity at the stage of metaphase is 
smaller than before, and the poles of the spindle become drawn 
closer together. The development of the spindle proved very 
difficult to study, and its history is discussed later in the paper under 
the head of spindle formation. 
The accumulations of kinoplasm at the poles of the spindle are 
very characteristic and resemble the centrospheres described by 
Davis (18) in the tetraspore mother cell of Corallina, except that 
the latter have well-defined radiations. The chromosomes when 
arranged in the equatorial plate are readily counted if viewed in trans- 
verse sections of the spindle (fig. 7), as well as during prophase 
(figs. 3a, 3b), and the number is clearly 20. Granular fragments of 
the nucleolus are always present in the nuclear cavity during the 
metaphase, after which they disappear. 
The duration of metaphase is rather long and the centrosphere- 
like Structures persist until late anaphase. When each group of 
daughter chromosomes passes to the pole of the spindle, there are left 
only a few fibrils forming a central spindle between them (fig. 8). 
After anaphase the kinoplasm intrudes into the nuclear cavity and 
the central spindle gradually disappears (fig. 9). The kinoplasm 
thus surrounds the groups of daughter chromosomes, and the centro- 
Sphere-like structure loses its distinct differentiation and becomes 
‘ cloudy mass of kinoplasm without a clearly defined boundary 
(fig. 9). 
Each group of daughter chromosomes, which during anaphase 
had a flattened form, becomes more or less spherical, with a small 
Space within (fig. 10). The mass of chromosomes surrounded by 
Stanular kinoplasm comes to lie in nuclear sap or caryolymph, and 
