516 Schwartz.—Parasitic Root Diseases of the Juncaceae . 
side, this cruciform structure is seen to consist of the elongated karyosome 
encircled by an equatorial chromatic ring or plate, the relation of the 
karyosome to the ring being that of an axle to the rim of a wheel. I have 
not observed any splitting of this plate, though in all probability this 
occurs. The next stage, which, however, I have not so commonly seen, is 
similar to the dumb-bell-like stage observed in 5 . Veronicae , and is doubtless 
formed by the splitting of the plate and the passage of the two halves, one 
to each extremity of the elongated karyosome, which then becomes very 
slender. From this point the completion of the division is easy to follow ; 
the equatorial portion of the original nuclear membrane disappears, and 
the nuclear membranes of the two daughter-nuclei are completed by the 
formation of a new transverse piece of membrane. Figs. 2, 3, and 4 show 
the various stages described above. 
The akaryote stage and the sporont . When the parasite is about to 
form its sorospheres, i. e. when the schizont is about to be transformed into 
the sporont, it is observed that the amoebae assume a spherical or ellipsoidal 
shape, the nuclear membrane disappears, and the karyosome diminishes in 
size and finally disappears also, so that we have a number of vacuoles more 
or less circular in outline situated in the spherical mass of plasma. This 
stage is shown in Fig. 18. In the case of those cells which are completely 
filled with a single parasitic amoeba a similar change takes place, but in this 
case the organism retains the shape of the cell. This stage is followed by 
the appearance of granules and irregular masses of chromatin forming fresh 
nuclei in the vacuoles referred to. The protoplasm of the amoeba collects 
around these freshly-formed nuclei, and the amoeba thus separates into 
a number of well-marked amoebulae, each having a single nucleus and 
a small quantity of surrounding protoplasm. 
In this condition the nature of the parasite is completely altered, and in 
place of the plurinucleate amoeba we have a number of small uninucleate 
independent amoeboid organisms, which, while quite distinct from one 
another, nevertheless tend to aggregate into masses either of more or less 
spherical shape or to loosely fill the root-cells. These amoebulae are to be 
seen in Figs. 17 and 23. 
The nuclei of these amoebulae then undergo two ordinary mitoses, the 
spindle formed in the latter of these being markedly smaller than that in the 
former, thus indicating a reduction division. During the progress of these 
two nuclear divisions, polar radiations may be seen proceeding from each 
pole, doubtless due to the presence of centrosomes, which bodies, however, 
I have not actually been able to see. Owing to the minuteness of the 
nuclei, which are more difficult to observe than those of .S. Veronicae , it 
was found impossible to ascertain the number of the chromosomes. I have 
observed no conjugation of nuclei either at this or any other stage of the 
life-history of the parasite, although it might take place after the germina- 
