Cytology of a new variety of Achlya amencana . 155 
Fig. 39, were carefully examined in this stage and it could 
be clearly made out that the skein was a very loose one, 
showing from four to five roughly parallel, but occasionally 
anastomosing strands in surface view. These strands were 
unequally thickened and their position could be shown, by 
following them to the margin of the nucleus, to lie immediately 
under the nuclear membrane, probably almost, if not quite, 
in contact with it. The centre of the nucleus was generally 
occupied at this stage by one or two small nucleolar fragments 
and a clear substance, staining a faint dusky-red, with the 
double stain. Although the size of the object deterred me 
from attempting to distinguish the longitudinal splitting of 
the coiled thread, careful attention was paid to the genesis 
of the skein, and the impression was gained of the chromatic 
material passing out from the central mass until nothing was 
left behind but the nucleolar fragments. If this view be 
correct, the nucleus of Achlya does not differ greatly from 
that of the higher plants. For its size it is relatively rich 
in chromatin and nucleolar matter, and the necessities of the 
case lead to an intimate mechanical mixture of these two 
nuclear substances. 
The nuclei at this stage, and especially in those which 
immediately follow it, are very difficult to fix properly. They 
seem to collapse. In any section of an oogonium few nuclei 
can be recognized by definite morphological characters. 
Some of them, however, in almost every section were found 
suitable for study, and special attention being paid to them 
such results as appear in Figs. 36 to 40 come before us. 
Small bits of the o'ogonia are alone represented except in 
Fig. 39, where the nucleus of an antheridium appears as well. 
Figs. 36, 37 and 38 represent the nucleus in the monaster 
condition, Figs. 36 and 38 from the side, and Fig. 37 from 
the pole. Remains of the nucleoli are still to be seen at 
this stage. A fragment of a nucleolus is represented in 
Fig. 38. There was a similar fragment in the nucleus repre- 
sented in Fig. 36, exactly behind a chromosome. Very few 
nuclei were seen in this stage and Fig. 36 represents the 
