26 BULLETIN 1053, IT. S. DEPARTMENT OF AGRICULTURE. 



He found the optimum to be 35° C. (95° F.), the minimum 5° <& 

 (39° F.), and the maximum point 44° C. (Ill F.). 



Lenzites trabea 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 seriaMs grows at about the same rate as Lenzites sepiaria y 

 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.) 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. Lentirms 

 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 OP 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 (Merulius lacrymans) 

 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 Goniophora 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 



