THE EFFECTS OF HYPERTONIC SOLUTIONS. 
455 
Fig. 21 shows a still more irreg’ular anaphase. In this 
case the whole mitotic figure has been affected. Tliere is 
no trace of asters or spindle-fibres, all that can indicate 
their existence being *a region of sliglitly denser and moi’e 
darkly staining protoplasm round the chromatin groups. 
The effect of the hypertonic solution npon the centro- 
somes is to cause them to become granular and to contract. 
In normal eggs the area of the centrosome is comparatively 
large and vesicular, as has been figured by Boveri and many 
other authors. They do not stain with iron-htematoxylin, 
and are quite free from granules. Tlie ceutrosomes of fig. 
18 are somewhat granular and more darkly stained than is 
normal. The extreme effect of the hypei’touic solutions, 
however, is to cause the centrosomes to contract into com- 
pact but irregular masses, which stain as darkly as the 
chromatin in the nucleus (fig. 21, etc.) (Fig. 33 shows the 
contracted centrosomes still at the centre of normal asters for 
series G.) The chromosome groups of fig. 21 are shown 
enlarged in fig. 63. It will be seen that the centrosomes are 
entirely degenerated, although the chi-omosomes are only 
somewhat swollen. 
Extreme cases of the degeneration of the nuclear structures 
is shown in figs. 22, 24. In fig. 23 a few chromosomes can 
still be detected as rod-like bodies, although this is somewhat 
doubtful ; while in fig. 22 all that remains of the numerous 
rod-like and V-shaped chromosomes of the normal egg is 
represented by irregular masses of chromatin. 
Fig. 25 shows a telophase in which all trace of the achro- 
matic parts of the nucleus have disappeared. At each 
polar area is a group of normal chromosome vesicles arranged 
as in a normal egg. "Within the lower group is seen a 
darkly stained vesicle which is exactly comparable to those 
found in series B, and to those found in the hybrid eggs of 
Echinus esculent us d x E. acutus $. Outside each 
group of vesicles are irregular darkly stained masses, which 
apparently represent the degenerated centrosomes. In spite 
of the entire loss of the individual nature of the chromosomes 
