1013] - - YAMANOUCHI—ZANARDINIA 3 
what time of day or night the material was fixed. After the plant 
became 5 cm. or more in diameter, mitosis was much more frequent 
near the margin of the thallus or in hairs growing from the margin. 
After the plant reaches the adult size (8-10 cm. in diameter), the 
figures are very rare in the inner tissue and only occasionally found 
in superficial layers. 
The cells of Zanardinia have quite thick walls, which are thickest 
in the huge inner cells and less thickened in the cells of the super- 
ficial layers that contain more numerous plastids. The plastids 
take stains with avidity, and it was more difficult to bring out the 
details of the mitotic figure than in Cuéleria and Fucus. The 
nuclei in the resting stage, in almost any part of the thallus, are all 
about the same size and are a little larger than the plastids. Each 
contains a small, deeply staining nucleolus, which lies in the center. 
The remainder of the nuclear cavity is almost wholly occupied by 
a large body of karyolymph, and a 
few scattered chromatin granules lin- 
ing the nuclear membrane. 
One of the conspicuous features of 
the resting nucleus of Zanardinia is 
the fact that outside the membrane 
there are frequently a number of 
deeply staining globules of irregular. 
size. These globules are so close to 
the membrane that for some time I 


Fic. 1.—Portions of vegetative 
was in doubt whether they were filaments: a, of zoospore-bearing 
within or without the membrane. Plant; 4, of gamete-bearing plant; 
nucleus with chromatic accumu- 
metal study, however, showed clear- lations along the outside of the 
ly that certain of them are outside the membrane. 
membrane and yet in close contact 
with it (fig.1). As the nucleus increases in size and the chromatin 
granules within increase in quantity, delicate chromatin fibrils of 
irregular size appear among the granules. During this increase of 
chromatin granules, the deeply staining globules outside the mem- 
brane decrease, and finally disappear. A comparative study of 
many such cases has convinced me that the globules are quite 
closely allied to the chromatin and seem to pass readily through 
the nuclear membrane. 
