120 
BRITISH GALLS 
swollen part. The perithecia are the flask-shaped bodies 
containing the long needle-like spores. This fungus is widely 
distributed in the south of England, and does much mischief 
in some districts, where it attacks many pasture grasses. 
Protomyces macrosporus infests various umbelliferous plants, 
giving rise to conditions well shown in Plate XXVII., 
in which we see a large indurated swelling on the stalk 
of the Hemlock Water Dropwort, and numerous swollen 
seed-vessels. The tumefactions are at first pale yellow, 
then pinkish, and finally brown. They contain the spores 
which are formed in the continuity of the mycelial hyphae. 
These galls may be found from May to October ; they are 
very uncommon. 
There are some excellent photographs in Connold’s “ Oak 
Galls ” of the cankerous growths commonly seen on the 
branches of young Oaks in many counties. They are 
attributed to the fungus Dichaena quercina , but mycological 
authorities agree that this is not at all likely, and the 
cause of these tumours still awaits investigation. The 
first indication is rounded swellings about the size of peas, 
these coalesce and not infrequently girdle the stem. They 
grow slowly, and in a few years become deeply fissured. 
I have never observed a fungus upon these hypertrophies. 
Connold also figured, in “ Plant Galls,” roots of Araucaria 
imbricata with large tumours, which he attributed to the 
presence of Peridermium elatinum; also similar growths on 
Hazel, Sallow, etc. There is a considerable collection of 
wood tumours in the Haslemere Museum on stems and 
branches of Scots Pine, Cedar, Hazel, Elder, Holly, Larch, 
Horse Chestnut, Beech, Birch, etc., and on roots of Scots 
Pine and Vines, but in no instance is it possible to state with 
confidence the primary cause of the overgrowth. It may 
have resulted from mechanical injury to a bud, from insect 
or fungus irritation, or from the presence of a bacterium. 
