GOLDSTEIN: PLANTS AFFECTED WITH Mosaic DISEASE 263 
Often as the bodies slowly rotate they seem to roll along 
the protoplasmic threads of the host cell. This movement seems 
quite independent of the rate of streaming of the cytoplasm of 
the host cell. The bodies do not all move along at the same rate. 
In fact they often pass one another. One may turn back or 
move across the cell, while the others continue their way length- 
wise of the cell. 
The general interrelations of the X bodies and the other 
constituents of the cell can be even better seen perhaps under 
lower magnifications. In the cell shown in figure 3, drawn 
- under a magnification of 450 diameters, eight X bodies were 
found. Here also the nucleus is seen imbedded in a mass of 
cytoplasm from which streaming threads arise. Along the 
threads are very many small pale green chloroplasts. In this 
cell as noted are three large X bodies and five very small ones. 
They all have a finely granular structure with coarser granules 
which showed what was probably Brownian movement. These 
X bodies were constantly changing their positions in the cell. 
The streaming cytoplasmic threads were also constantly taking 
new positions, lying now across the cell, now diagonally longi- 
tudinally through the cell, or merging in the cytoplasm of the 
primordial utricle. 
In figure 4, I have shown a normal hair cell from a healthy 
leaf for comparison with these cells containing the X bodies. 
It is obvious at once that there are no conspicuous differences 
in the distribution of the cytoplasm and its relations to the 
nucleus between such a cell and the cells with the X bodies. 
The position of the nucleus, the streaming and constantly chang- 
ing cytoplasmic threads, and the distribution of the very small 
pale green plastids, resemble in general the same structures and 
conditions found in the cell shown in figure 3. 
As noted the nucleus may lie suspended in the cell by cyto- 
plasmic threads or be pressed close to the wall of the cell. Usu- 
ally the nucleus lies in the primordial utricle against the wall 
of the cell. I have seen the nucleus, in a hair cell containing 
the rotating X bodies, move out from the wall with the radiating 
streaming cytoplasmic threads about it, and hang suspended 
in the cell vacuole without further changing its position during 
a period of observation lasting five hours. The nuclei of the cells 
in figures 3 and 4 were being carried by the streaming cyioplasm 
