Veronica Ckamaedrys caused by Sorosphaera Veronicae. 39 
place in the ordinary mitotic way, as shown in Figs. 11, 12, and 13. 
The result of these two mitoses is a reduction in the size of the amoebulae 
and of the karyokinetic figures, which are markedly smaller in the second 
division than in the first. At the close of the second division two adjacent 
amoebulae are often to be seen in contact, suggestive of a conjugation, but 
this appearance is more probably due to the fact that they are not separated 
from each other. 
During these mitotic divisions, at the pole of each spindle, radii may 
be seen which probably proceed from a centrosome, though we have been 
unable to see this body. The amoebulae are now found in the cell in 
loosely aggregated masses, near the margins of which are often to be seen 
a few individuals independent of the general mass, as seen in Fig. 14. 
These aggregations become more intimate till the amoebulae are fused into 
spheroidal masses (Fig. 16); each amoebula, however, becomes by degrees 
more distinct as it secretes for itself a wall presumably of fungal cellulose 
(Fig. 17). This wall slowly thickens, and the arrangement of the amoebulae 
isThen such that a hollow sphere results, in which the central cavity is 
surrounded by the spores, which are wedge-like in shape; this is the 
sorosphere, and is to be seen figured in Fig. 4. 
The size of the sorosphere and the number of spores may vary con¬ 
siderably ; occasionally two sorospheres become fused together, forming 
a compound sorosphere of an oblong or ellipsoidal shape. There is 
a reticulate vesicular nucleus at the broader end of each wedge-shaped 
spore. 
When this stage is reached the tumour commences to rot, and is 
invaded by moulds and bacteria, liberating the sorospheres. What interval 
of time elapses before the spores are liberated from the sorosphere we have 
not determined, as observations of hanging-drop cultivations have shown 
no definite liberation. We have also not succeeded in cultivation experi¬ 
ments to a sufficient extent to be able to give an account of the germination 
and subsequent behaviour of the spore; the nearest approach to success 
was gained by inoculating a sterile infusion of Veronica leaves with boiled 
water in which portions of dead tumours had been placed. In this mass, 
which of course was no longer sterile, bacteria and moulds made their 
appearance, and, after an interval of some fourteen days, numbers of 
amoebae were found in a state of activity in a drop taken from the debris 
at the bottom of the tube. These amoebae, which each contained only a 
single nucleus, were later on found in an encysted condition. 
Mode of Infection of Veronica Plant. The earliest tumours are to be 
found in the region of the growing point of the stems. This point comes 
out clearly in longitudinal sections, and it is possible to trace a series of 
infected areas getting larger and larger as one works down the stem. 
When the invasion is extensive the whole future of the shoot is modified, 
