Nov. 3.1923 Five Molds and their Penetration into Wood 
227 
That cytolytic enzyms are produced by fungi, including some of those 
classed as molds, has been pointed out by various investigators (j, 2 
P . 417, 3> 4 P • 2 3*> 7 ,13 , 14* J 5 > 16, i7, P • 33i) - Some report attacks 
on the middle lamella, others on the cell walls. There is little which bears 
directly on wood although Ward ( 22) concluded: “It certainly looks 
as if Penicillium may be a much more active organism in initiating and 
carrying on the destruction of wood than has hitherto been supposed, 
and that it is not merely a hanger-on or follower of more powerful wood- 
destroying fungi. It is also doubtless very independent of antiseptics.” 
Finally, as has been pointed out, it is clear that certain molds may 
actually bore through cell walls, or produce a surface thinning, presuma¬ 
bly through the activities of cytolytic enzyms (with an effect which 
though probably limited is similar to that of a wood-destroying fungus). 
Moreover, conditions which foster the growth of molds will also permit 
other fungi to develop and spread. Hence, moldiness of material is an 
indication that it may have been subjected to more or less undesirable 
conditions. Lastly, molds (commonly Penicillium divaricatum) are fre¬ 
quently isolated from seriously decayed or rotted wood, indicating that 
the molds flourish in that environment. 
With these facts in mind it is obvious that the prevention of the mold¬ 
ing of lumber is desirable. Although no method of perfectly controlling 
it is known, a number of helpful methods have been, or are being devel¬ 
oped, by experiment. The conditions favorable to the development of 
molds in wood are abundant warmth and moisture. Free access of air 
tends to lower moisture content. Hence the open piling of the material 
with good opportunity for circulation of air is of considerable assistance 
in preventing the development of molds. This may also be accom¬ 
plished with varying degrees of success by treating the lumber with anti¬ 
septic solutions. In some localities, and under ordinary conditions, a hot 
solution of 4 to 8 per cent sodium carbonate (soda ash) or 5 to 11 per cent 
sodium bicarbonate (baking soda) may be used successfully as a dip for 
the stock as it comes from the saw. These are not perfect protectors 
under severe conditions, but either will assist in keeping the stock clean. 
There are other chemical dips, such as mercuric chlorid (0.1 per cent 
solution) which, because of its poisonous character, is not desirable, or 
sodium fluorid (3 per cent solution) which will generally prevent blue 
stain but has not been found so successful with molds in general. Kiln- 
drying is an effective method of preventing infection and of killing molds 
already present in lumber. Sometimes molds may develop abundantly 
in the early stages of a kiln run. Their growth may be stopped, however, 
by steaming the stock for one hour at 170° to 180° F. This treatment, 
since the air is saturated, does not too rapidly dry the lumber. 
SUMMARY 
Pure cultures of five so-called molds, after growing in flasks for two 
years were found to have developed mycelium in the wood below the sur¬ 
face of the inch test blocks of aspen, Sitka spruce, red oak, and 
white oak. The mycelium was present in the center of the hardwood 
blocks. The penetration was chiefly through the natural openings—that 
is, vessel or tracheid cavities, in the case of Aspergillus niger and Cera - 
tostomella sp. 
Monilia sitophila and Penicillium divaricatum showed the greatest 
amount of development in the different wood elements and a marked ten- 
