[VoL. 3 
446 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
range from a minimum of 5°C. to a maximum of 44°C., with 
35°C. as an optimum temperature. This optimum holds for 
the strain of this species that I used, but the total range of 
temperature was not determined. A question still remains 
whether the optimum temperature for growth is an optimum 
for the complex of enzyme activities which take place during 
decay. With this in mind the cultures were maintained at 
25-30°C., since these temperatures аге at least conducive to 
growth, and enzyme action in vitro is rapid within these 
limits. 
(3) Given some specific wood as a suitable substrate and 
a favorable temperature, then the growth of L. saepiaria will 
be related to such other factors as porosity, water content, 
oxygen tension, and abundance of stored starches or other 
food materials in the wood. The oxygen content of wood is 
necessarily related inversely to water content, provided there 
is water in excess of that imbibed by the tracheid walls. Vari- 
ation in the imbibed water must influence the degree of 
humidity of the air in the lumen of the tracheids, and doubt- 
less the humidity of this enclosed air plays a róle in the 
growth of the fungus through the wood. Another factor 
which influences the oxygen content of wood is the average 
size of the cell lumen. This decreases in size from the spring 
to the late summer wood, for in the latter the lignification in- 
creases the thickness of the walls at the expense of lumen 
capacity. High specific weight is directly related to the 
amount of summer growth (Johnson, '93). This necessarily 
means that as the specific weight of the wood increases the 
oxygen content would be decreased. 
Miinch (209) has shown by numerous experiments with 
various forms of wood-destroying fungi that air content is an 
important factor influencing the entrance of fungi. The 
greater number of the forms which he used have a high air 
requirement. The quantity of wood fibre is also important. 
He mentions the fact that narrow annual rings are more 
resistant than broad ones, because there is less capacity for 
air in the narrower. In specimens of wood where only some 
rings are decayed the decayed rings prove to be the more 
