Jan. 17,1916 
Plenodomus fuscomaculans 
763 
We may now consider other factors in the light of this theory. Experi¬ 
ment has shown that aeration is essential for reproduction. The action 
of light upon the protoplasm is dependent upon the oxygen supply. 
Aeration may work to continue the oxidizing process by the removal of 
end products, thus allowing oxidations to proceed to completion. In 
many cases recorded in the literature the effect of transpiration is to 
further the exchange of gases. The action of low temperature was to 
check growth, and pycnidium production was found to start. Euler 
(1909) states that lowering the temperature affects the oxidation process 
to a lesser degree than it affects other processes. 
The action of the acid reaction is interesting and confirmatory. So 
far in this discussion the mechanics of the oxidation have not been con¬ 
sidered. Oxidations in plants are generally believed to take place through 
the activity of oxidases of various sorts. As is well known, light acti¬ 
vates this type of enzym, although it is detrimental to such enzyms as 
diastase (Euler, 1909, p. 97). The pronounced and sudden blackening: 
of cultures about to produce pycnidia is very significant and can be best 
explained by the oxidation of some leuco compound by an oxidase 
(Kruse, 1910, p. 787). Some oxidases are known which work better in 
a slightly acid medium. We have seen that for this organism an alka¬ 
line medium was prejudicial to reproduction. The effect of acid reaction 
in favoring the reproductive process has not been explained, but it may 
have some connection with the enzymotic process. At any rate, an 
oxidation of oily stuffs to fatty acids would give a medium suitable for 
further activity of these ferments. 
The formation of pycnidia in the aerial mycelium and in fact the whole 
series of complex reactions which Klebs (1900) has associated with “Luft 
leben ” become much more comprehensible if we view them from the point 
of view of oxidation. 
The replacement of the light factor by hydrogen peroxid thus becomes 
of great importance in reducing to simple terms the phenomena encoun¬ 
tered. Eight can unlock in suitable mycelium the reproductive process. 
This it does by its catalytic influence. The action may be due to the 
activation of oxidases along with the inauguration of a reaction (acid) 
favorable to their continued action; but this oxidation thus set up does 
not proceed to reproduction if the growth process is consuming the 
energy. If growth is not able to proceed, owing to scanty food supply 
or some checking influence, then the catalytic action of light inaugu¬ 
rates a building of the stored foodstuffs into complex fruiting bodies. 
This general discussion may now be summarized. In the historical 
portion of the paper it was seen that the environment may be viewed as 
a directive and collective force which can be utilized for unfolding the 
life history of an organism. The great generalizations of Klebs are 
broad, and by their very broadness make possible acceptance in a wide 
