1912] GRIGGS—RHODOCHYTRIUM 159 
shows, what I have myself observed, that they may pass through 
a process of vacuolation accompanied by the extrusion of chromatin 
analogous to that of the primary nucleolus. In Rhodochytrium 
such secondary vacuolation occurs but rarely, though some of the 
largest chromatin masses may break up in this way (fig. 49). But, 
as was shown in the account of mitosis, a large proportion of the 
chromatin spherules suffer the same fate as the old nucleoli, primary 
and secondary, of Synchytrium, namely dissipation in the cytoplasm. 
There is, moreover, a great variation in the size, composition, and 
behavior of the secondary nucleoli in Synchytrium (see Kusano 
18, p. 94), some of them (the earlier and smaller) being almost, 
if not entirely, pure chromatin, and undergoing but little change 
in preparation for mitosis; while others (the later and larger) are 
plasmosomes with but little chromatic material. There is, there- 
fore, no question but that the chromatin masses of Rhodochytrium 
are homologous to secondary nucleoli, but it does not seem advisable 
to use that term in describing them, since there is no distinction 
between those which form the chromosomes of the spindle and 
those which perish. 
Mirosts.—The first mitoses of Rhodochytrium and Synchytrium 
are not so similar as are the primary nuclei, but they are of the 
same general type. Although very different from those found in 
most organisms, the first mitosis of Rhodochytrium, like the vegeta- 
tive condition of the primary nucleus, is not so widely aberrant 
as that of Synchyirium. Neither STEVENS nor KusANo was able 
to obtain an altogether satisfactory series of the prophases of the 
primary mitosis, and their figures do not supplement each other, 
but conflict to a certain extent. Both observed, however, a 
marked and peculiar production of fibers, STEVENS through the 
whole cavity of the nucleus, and Kusano especially in the region 
of the old nucleolus after the dissolution of the membrane. While 
the conditions found by these writers in Synchytrium differ greatly 
in detail from those in Rhodochytrium, the fibers would seem to be 
comparable to those seen in the early prophases of the present 
plant. If this interpretation is correct, the fibrous stage in Synchy- 
‘rium is not to be homologized with a spirem, but is rather a phase 
of spindle formation. The differentiation of the chromosomes, 
