Veronica Chamaedrys caused by Sorosphaera Veronicae. 41 
display a large deeply staining nucleus and nucleolus surrounded by 
granular protoplasm ; the diseased cells contain amoeboid parasites in 
close connexion with their nuclei ; these organisms are small and usually 
contain several nuclei. Occasionally mononucleate ones are to be seen, 
but it is impossible to be sure whether they represent the earliest stage 
or whether they are in reality portions cut in section from a larger body. 
In Fig. 3, the middle stage, we notice a considerable increase in 
the size of the infected cells, and to some extent of the healthy ones 
as well; these latter are crowded with starch grains embedded in the plasma. 
The amoebae have grown enormously in size, forming an irregular plas- 
modium in the cells, portions of which separate from the original mass and 
continue their development independently. Starch grains are also to be 
seen in the infected cells, in which, however, they are not nearly as plentiful 
as in the neighbouring healthy cells. 
Fig. 4 shows the final stage of development. Here the infected 
cells are mostly filled with the spherical sorospheres ; their protoplasm is 
scanty and their nuclei enlarged and degenerate. 
The Plant Nucleus . The changes which the plant nuclei undergo 
during the life of the parasite are interesting. At the time that infection 
takes place the early cambial cell is hardly differentiated from the other cells 
of the growing point; its nucleus and nucleolus are large and stain deeply. 
In the normal course of events this nucleus would become elongated, and 
would consist of a fine reticulate network of linin with two or more large 
collections of chromatin (nucleoli), but in the case of infected cells the 
nucleus and nucleolus retain their spherical shape. It is a matter of con¬ 
siderable interest as to how this minute parasite is able to select a pro- 
cambial cell for its development and avoid those other cells which do 
not retain their power of division as does the procambial cell. The varied 
grouping of infected and healthy cells in the tumours may be explained 
by the fact that the organisms may or may not be divided when cell 
division occurs; if division of the cell always included division of the 
organism we should get masses of infected cells surrounded by modified 
healthy cells; this, however, is rarely the case. 
The cell nucleus shares in the hypertrophy of the infected cell, and 
after a time there is a failure in the formation of a dividing cell-way, 
and though division of the nucleus takes place there is no actual cell 
division. This is shown in Figs. 38 and 19, which represent the nuclear 
division or mitosis taking place; as is seen from these drawings, the size 
of these nuclei is enormous compared with those of normal cambial 
cells. As our drawings show, it is at the close of the vegetative stage 
that the nuclear divisions are to be seen in their greatest development; 
with the commencement of the reproductive stage of the parasite the 
activity of the cell declines, and after the formation of the sorospheres 
