Davis. — Nuclear Studies on Pellia . 165 
must frankly admit the justice of such criticism, and recognize 
the value of this cautious attitude. It is possible that the 
asters divide, and the evidence against it is purely negative, 
but the writer’s disbelief is not founded on a hasty examina- 
tion. There are also some peculiarities that should be noted 
in this connexion. The kinoplasm displays a remarkable 
degree of mobility in the various positions which it takes 
around the nucleus. We have noted the condition where 
it is massed on one side (Fig. 22), but usually the material 
is distributed more evenly. If a nucleus be elongated ever 
so little in any direction one may expect to find accumula- 
tions of kinoplasm at the poles. It is not necessary that such 
a nucleus be preparing for mitosis, although such accumula- 
tions of kinoplasm are associated with conditions of prophase. 
The kinoplasm usually lies close to the nuclear membrane, 
but it may sometimes be found in masses somewhat removed, 
and when such accumulations organize asters (see Fig. 25) 
they are at a distance from the nucleus. As a rule, how- 
ever, the former conditions prevail, and kinoplasm before the 
differentiation of the aster appears as in Fig. 24, and after 
the development of these elements presents the structures 
shown in Figs. 26 and 27. 
In the mobility of the kinoplasm we may have the explana- 
tion of the apparent development of two asters independently, 
and as far remote as possible from one another, sometimes 
touching the nucleus, and sometimes at a considerable distance 
from it (Fig. 25). Portions of the kinoplasm seem able to 
act in a great degree independently of other parts to accumulate 
material, and at the proper time organize asters. 
Certain peculiarities of the aster should be noted before 
attempting to discuss its origin. The writer has preparations 
and is familiar with the asters of Fucus> Sphacelaria , and 
Dictyota , structures more clearly differentiated than the asters 
of Pellia. Of these three the aster of Fucus is perhaps the 
least sharply defined in its minute structure, although most 
conspicuous as a whole. The aster of Pellia resembles that 
of Fucus in that the radiations proceed from a rather vague 
