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On twigs. Twigs from oak or sycamore, collected in the early spring, 
are provided. OBSERVE :— 
9. That the twigs are (or were) still alive and the buds formed 
the previous autumn have reached maturity. 
10. The fruiting stage of the pathogene formed under the cork- 
layer, raising it up in pimple-like pustules. Later the cork-layer is rup- 
tured and the fruit-bodies are exposed. . 
11. The terminal portion of the twig is partially or entirely 
invaded by the pathogene, as indicated by the distribution of the fruit- 
bodies noted above. 
Twigs thus affected may put out leaves in the spring which, however, 
usually wither and die before they reach full size. This is due to the rapid 
advance of the pathogene in the twigs, killing them. 
On the branches of sycamores. In the affected branches of sycamore 
NOTE -— 
12. The small.diseased areas around the bases of the twigs,— 
cankers. 
13. Larger cankers with scars of old twigs at the center, showing 
the origin of the canker. 
14. The cortex of the bark raised up. and broken through by 
the fruit-bodies of the pathogene. In some cases these fruit-bodies 
are gone and only a cavity is left in the bark. 
15. Older cankers in which the dead bark has fallen away and 
the wood is left bare. 
16. That callusing takes place rapidly in some cases and the 
open wound is covered. 
17. That swellings of irregular shapes are often formed at points 
where witches’-brooms originate. 
ETIOLOGY 
The anthracnose of svcamores and oaks is caused by the ascomycetous 
fungus, Gnuomonia veneta (Saccardo and Spegazzini) Klebahn. Previous 
to the discovery of the ascigerous stage of the pathogene, it was known 
by several names because of the variable types of asexual fruit-bodies 
which the fungus forms. The commonest of the names for the imperfect 
forms is Gloeosporium nervisequum (Fuckel) Saccardo, this being the name 
for the acervulus-stage which occurs on the lesions on the leaf-blades 
and petioles. On dead leaves, a pycnidial stage is formed,—the 
Sporonema stage and on the twigs, a pseudopycnidial form,—the Myxospor- 
ium stage. 
Life-history. The polymorphic character of the asexual fruit-bodies 
found on the different parts of the hosts which are attacked, makes the 
life-history of this pathogene complicated. Their identity was established 
by Klebahn in 1905. Klebahn also connected the polymorphic conidial 
stage with the ascosporic stage which is developed on overwintered leaves 
on the ground. 
‘The Primary Cycle may be initiated by several sorts of inocula. No 
definite investigations have been made to determine the relative effective- 
ness of these in nature. The possible primary inocula may be, ascospores 
from overwintered leaves, conidia from the Myxosporium stage on twigs 
and cankers, and conidia from the Sporonema stage on overwintered 
