180 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
those found in Corticium efjuscatum are the smaller size of the latter 
species, and the greater tendency of its conidiophore to become com¬ 
pound. Brefeld describes branching and proliferation of the coni¬ 
diophore in Polyporus annosus, particularly in old cultures, but these 
phenomena are only occasional. Indeed, in the writer’s study of this 
species, he has almost never seen any signs of either branching or 
proliferation in cell cultures, while under exactly similar conditions 
Corticium efjuscatum always shows both in abundance. Hence this 
may be regarded as the normal and characteristic method of growth 
in the latter species, while it is more unusual in the former and is 
rather the result of external conditions than inherent in the species. 
Cultivation of conidia. — The conidia of Polyporus annosus ger¬ 
minate readily. On the contrary considerable difficulty was experi¬ 
enced in securing germination of the conidia of Corticium efjuscatum 
although many different media of various degrees of concentration 
were employed. Only occasionally did a spore show any signs of 
germination, and in these cases the development seldom progressed 
beyond the formation of a germ tube from 10 to 15 y in length, the 
growth being not infrequently stopped by the formation of a chlamy- 
dospore (pi. 22, fig. 103-104). 
In cases where successful germination was secured (pi. 22, fig. 100- 
102), the process was slow,— both in the first appearance of the germ 
tube (after from two to five days) and in its initial growth,— facts 
which apparently indicate low vitality. Moreover, contrary to the 
rule in the case of such small spores, the conidium does not swell 
appreciably in germination. Hence the germ tube is necessarily 
small, 2.5 y in diameter, but it soon, sometimes immediately, produces 
hyphae of normal size. This increase in diameter is sometimes 
secured by a gradual broadening as the germ tube grows in length 
(pi. 22, fig. 101), and sometimes by a bulbous terminal enlargement 
from which a hypha of normal size arises a little later (pi. 22, fig. 102). 
This period appears to be a critical one, and the majority of germi¬ 
nating spores perish at this point, although vitality may be preserved 
by the formation of a small chlamydospore in the germ tube, as was 
stated above. If the increase in size is safely secured, more rapid 
growth follows, and a normal primary mycelium results (pi. 22, fig. 105). 
Frequently conidia germinate in situ when they chance to be 
submerged, putting forth germ tubes while still attached to the coni¬ 
diophore (pi. 22, fig. 98). From this it was thought that the small 
percentage of germination in cell cultures might be due to early loss- 
