38 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 
nation, but excellently adapted to dissemination by insects or drip- 
ping water. The practical application of these facts is obvious. If 
secondary spores occur outside of artificial cultures, there is no place 
more suitable for their formation than in the structures of wet oc- 
cupancy referred to. In these structures, where conditions are moist, 
there would be insects or animals, such as sow bugs and cockroaches, 
and there is commonly dripping water, precipitation water upon cool 
masonry, around cold-water pipes, etc. 
OCCURRENCE IN BUILDINGS OF THE SECONDARY SPORES OF 
THE FUNGI STUDIED. 
The step following the demonstration that oidia can disseminate 
fungi, such as Lenzites sepiaria and L. trait ea, is to prove that such 
oidia occur naturally in buildings. The outstanding fact is that 
many European writers have suggested the importance of the sec- 
ondary spores in the economy of the fungus, if found naturally, and 
that no one has yet reported such occurrences. The writer has little 
information on the subject. The only secondary spores found in mills 
are the chlanrydospores on the mycelium overgrowing the gills of 
fruit bodies of Lentinus lepideus (PI. V, fig. 6). These are formed 
quite abundantly, but thus far nothing is known of their ability to 
disseminate the fungus. The spores which the writer found were 
on old fruit bodies, and tests as to their ability to germinate failed. 
There is, of course, the possibility that freshly formed chlamydo- 
spores may germinate, and, if so, they would disseminate the fungus 
much as do the basidiospores which are overgrown and imprisoned 
by the chlamydosporic mycelium. This means of dissemination 
would appear to be not so efficient a method as by the basidiospores 
which they replace, because the basidiospores should be lighter and 
hence capable of wider dissemination. 
It is known that certain fungi do form superficial mycelium within 
the structures referred to in these studies as well as out of doors. 
Falck (15, p. 154) relates that the fruit-body-forming mycelium 
(fruktifikative Oberfldckenmycel) of Lenzites sepiaria is found on 
moist places on beams, and he states (15, p. 143) that it is capable 
of producing oidia, although he has not reported the finding of these 
oidia in buildings. The writer has examined some superficial myce- 
lium of Lenzites sepiaria and L. trabea upon planks secured from 
mill roofs, but the presence of oidia or chlanrydospores as yet has not 
been definitely established. 
SUMMARY. 
In textile and paper mills prevailing conditions of humidity and 
temperature provide a favorable environment for the development 
of wood-decaying fungi. Under such conditions poorer grades of 
