26 BULLETIN 1053, U. S. DEPARTMENT OE AGRICULTURE. 
He found the optimum to be 35° C. (95° F.). the minimum 5° C. 
(39° F.) 3 and the maximum point 44° C. (111° F.). 
Lenzites trdbea makes a moderately rapid growth, covering the 
dish in seven or eight days. It grows fastest at 28° C, although 
nearly as rapidly at 30° C. It grows only very slightly at 40° C. 
(104:° F.). 
Trametes serialis grows at about the same rate as Lenzites se plana. 
covering the dish in 7 days. The optimum for T. serialis is at 28° C. 
(82° F.). No growth occurred at 34°' C. (93° F.), and at 3° C. 
(37° F.) none was noticed until after 39 days, when it was seen to 
be alive and barely growing. Fomes roseus is a more slowly growing 
organism, taking 11 days at the optimum temperature (30 c C.) to 
cover the 10-cm. Petri dish used. At 3° C. there were signs of 
growth in 12 days, but very little at 36° C. (97° F.) and none at 
40° C. (104° F.). Upon microscopic examination it was seen that 
at 40° C. hyphse had started to grow, but had died. Lentinus 
lepideus also grows at a moderate rate ; in most of the tests the dish 
was not quite covered in 12 days. Its optimum was found to be 
28° C. (82° F.). Its range of growth was narrower than that of 
the other three fungi. No growth was noted at 8° C. (46° F.) in 
12 days, and at 36° C. (97° F.) there was less than 1 mm. in the 
same period. No growth was visible at 40° C. (104° F.). 
SECONDARY SPORES. 
INTRAMURAL DISSEMINATION OF FUNGI CAUSING DECAY. 
One of the most interesting problems in connection with the decay 
of building timbers is that of the intramural dissemination of the 
causal organisms. Abundant proof is at hand to attest the activity 
of the mycelium in spreading decay throughout a building by direct 
growth from one timber to another. Falck (16, pp. 245-247) has 
shown how the mycelium of the dry-rot fungus (Mendius lacrj/mans) 
can grow through structures and even for some feet over brick and 
stone masonry from one piece of timber to another. Wehmer (61) 
has shown the same for cultures of Conlophora cerebella. The dis- 
semination of M. lacrymans by means of rhizomorphs is also well 
known (cf. Falck and others). The dissemination by means of 
basidiosporic. fructification has already been mentioned. While con- 
ditions in textile and paper mills may occasionally favor the forma- 
tion of fruit bodies, of certain species at least, conditions also may 
prevail which will likewise prevent the formation of such fruit 
bodies. It has been shown that Trametes serialis can fruit and cast 
spores in the dark. On the other hand, Lenzites sepiaria can not 
form normal fruit bodies in the absence of light (see Falck. IS. for 
reference and discussion), and the same is true of Lentinus lepideus 
