36 Blomfield and Schwartz.—Observations on the Tumours on 
result of which we embody in this communication. As to the distribution 
of these tumours, up to the present time we have only been able to find 
the disease on V. Chamaedrys , notwithstanding the fact that we have seen 
large crops of V. heaerifolia growing in the immediate vicinity of diseased 
Chamaedrys plants. V. Chamaedrys is common in our district (Sevenoaks), 
but diseased plants are rare and mostly to be found in damp shady 
situations. 
Nematode worms cause swellings and twistings of Vero?iica stems 
which often simulate, to some extent, in outward appearance those due to 
the attack of Sorosphaera. 
The tumours themselves are to be found in various parts of the plant, 
their most common form being that of swollen stunted stems from which 
spring a few small deformed leaves ; young shoots springing up from the 
procumbent stems of Veronica plants are especially liable to attack. 
An infected plant may have tumours in all stages of development; stems, 
petioles, and leaves may all show signs of the invasion of the parasite, 
in the case of the leaves the small swellings being found along the line 
of their mid-rib; occasionally a tumour may be found involving only 
half of a stem, in which case the latter becomes bent or curled. The 
tubercles vary in size from that of a pin’s head to that of the last joint 
of the little finger; slugs are very fond of them, and possibly play a part in 
spreading the disease; those tumours which escape the attack of slugs 
finally become soft and rotten, the sorospheres are liberated by their decay, 
and the spores in all probability germinate in the soil, where the young 
amoebae live until they meet with fresh host plants to attack. 
We have been successful in producing tumours by sowing Veronica 
seeds in a pot and sprinkling them with water containing the sorospheres 
from dried tumours pounded with a pestle in the water. There was no 
evidence of any disease in the roots, many of the young roots being 
examined microscopically with reference to this possibility ; for this reason 
doubtless the parasite does little damage to the host plant, its effect is 
largely local, and we find no such destruction as that caused by Plasmodio- 
phora in cabbage plants. 
A drawing of a diseased plant is shown in PI. V, Fig. 1. 
It is obvious that the parasite with which we are concerned is closely 
allied to P. Brassicae in its structure, its chief point of difference being in 
the terminal phase of its life-history; accordingly we have availed ourselves 
of the most recent communications on that parasite by Nawaschin and 
Prowazek, the paper of the former being in ‘Flora’, 86. Band, l 899, and 
of the latter in ‘ Arbeiten aus dem kaiserlichen Gesundheitsamte ’. 1 
The material used in our investigation was all collected in the neigh¬ 
bourhood of Sevenoaks; the larger tumours were cut into small pieces and 
1 Twenty-second Volume, second half. Berlin, 1905. 
