560 BULLETIN 347 
meter in diameter. The spore horns from this type are also usually 
much stouter than those from the former type, and on the bark of old 
trees, where they arise from lines of confluent stromata in the crevices, 
a whole line of them may be united in a comb-like manner. The spore 
horns of both types are usually flat or irregular in cross section. This 
accounts largely for the way in which they curl. When dry they are 
hard and brittle and not easily detached or broken. 
Another form of pycnidia occurs on cut ends of stumps and logs, 
and also on both the wood and the inside of the bark where the latter 
has broken loose. These are superficial, single pycnidia (Fig. 87). A 
favorite place for them is on the inside of the 
‘bark whereit has drawn away from the stump 
around the top, after the tree has been cut. 
Also, when a log or a stump on which there was 
a canker is peeled, these pycnidia develop on 
Fic. 87.— Superficial the surface very quickly. Their production is 
Deed ts fe ge largely dependent on the water supply; this is 
ation illustrated by the fact that in dry weather they 
develop on the lower side of a log lying on the 
‘ground, but not on the upper side. In moist, shaded places they are long 
pear-shaped or conical, as shown in Fig. 87, or the base may be flattened 
out slightly on the substratum; but on tops of stumps — where they 
occur abundantly on the outermost four or five annual rings and where 
' the supply of moisture is not constant —they are flattened out on the 
substratum and do not stand out free as shown in the figure, and they 
also have more of a tendency to run together. In color they are deeper 
red than the stromata, but have light yellow, conspicuous, beak-like 
ostioles. They are surrounded by no stroma whatever and stand out 
free except as stated above. They measure about a quarter of a milli- 
meter in diameter and the same in height. The outer wall is perfectly 
smooth as seen under a hand lens. Often several pycnidia unite, but 
their ostioles remain distinct and give the appearance of a single 
pycnidium with several ostioles. 
Pycnospores 
The yellow tendrils are composed entirely of small, hyaline spores 
that are held together by a sticky substance the nature of which has not 
‘been carefully investigated. When the tendril is placed in water, it first 
swells considerably, then the binding substance dissolves and the spores 
float away free from one another. The spores average about 1.28 by 
3-56 w in size, and are oblong or cylindrical with rounded ends, or slightly 
oval, usually straight but sometimes slightly curved. The fact that they 
