360 M. M. Mercaur 
whose fibres radiate from the surface of the nucleolus. Where they touch the 
nucleolus triangular nodal thickenings of the films are seen. The chromosomes 
are granular. Coros. subl.-acetic acid, DELArreLD’s haematoxylin. >< 1600 diameters. 
Fig. 56. A nucleolus with central vacuole and minute peripheral vacuoles. 
Coros. subl.-acetic acid, DeLarretp’s haematoxylin. > 100 diameters. 
Fig. 57. A nucleus showing characteristic enlargement of the ends of the 
longitudinal fibres of the chromatin spindle, only a small part of the structures 
in the nucleus are drawn. Coros. subl.-acetic acid, DeLariELp’s haematoxylin. 
< 1600 diameters. 
Fig. 58. A nucleus in an early telophase of mitosis. In one end of the 
nucleus two of the chromosomes have fused by sending out a broad band of 
chromatin which unites them. There are eight chromosomes in this end. At the 
other end two of the chromosomes are constricted each into two. None of these 
chromosomes are yet united as in the opposite end of the nucleus. At the centre 
of the nucleus are a few alveoles of the achromatic foam which stain more deeply 
than the rest and are probably filled with dissolved chromatin from the “chromatin 
spherules’”. With the exception of these alveoles, none of the achromatic structures 
in this nucleus are shown, and only the larger fibres of the chromatin net are 
drawn. Coros. subl.-acetic acid, DELarreLp’s haematoxylin. >< 1600 diameters. 
Fig. 59. A very thin transverse section of a nucleus, showing the chromo- 
somes just beneath the nuclear membrane, also lines of achromatic granules, and 
four partially dissolved masses of chromatin (‘‘chromatin spherules”). The finer 
details of the achromatic structures were not clear enough to draw. Coros. subl.- 
acetic acid, borax carmine. >< 1188 diameters. 
Plate XIX. 
Opalina intestinalis. 
All figures are reduced one-fifth, to the magnification indicated. 
Fig. 60. A daughter cell with the nucleus in a late telophase of mitosis. 
Coros. subl.-acetic acid, Derarreip’s haematoxylin. > 808 diameters. 
Figs. 61—62. Two optical sections, through the upper and lower halves 
respectively, of the nucleus shown in Fig. 60. The chromosomes are seen to be 
united together by broad thin bands of chromatin. The transverse line near the 
upper end of Fig. 61 is a fold in the nuclear membrane. The finer chromatin 
fibres are not drawn nor are the fibres of the achromatic foam. Only a few of 
the achromatic granules are shown. The nucleolus is not drawn. Coros. subl.- 
acetic acid, DeLarreLp’s baematoxylin. >< 160 diameters. 
Fig. 63. An older daughter cell whose nucleus is nearly separated into two 
daugther nuclei, one of which shows eight distinct chromosomes, while in the 
other the chromosomes are mostly united as in Fig. 61. The drawing shows the 
chromosomes, the polar fibres connecting one set of these with the pole, and 
several faintly stained bodies, nearer the constricted center of the nucleus, which 
seem to be dissolving “chromatin spherules”. Coros. subl.-acetic acid, DELarrmip’s 
haematoxylin. > 808 diameters. 
Fig. 64. Outlines of the nucleus and anterior end of the body of another 
individual. >< 404 diameters. 
Fig. 63. The same nucleus as that shown in Fig. 64. It is in a late telo- 
phase of mitosis, the daughter nuclei being nearly distinct. Eight chromosomes 
were present in each daughter nucleus, as was shown when the animal was 
