THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 6 
VARIATION IN TOXICITY OF CHEMICAL SUBSTANCES TO DIFFERENT FORMS OF PLANT 
LIFE. 
A review of the literature on the action of various toxic agents 
shows that the different forms of plant and animal life often behave 
very differently toward the same chemical substance. However, on 
account of the complexity of the digestive and absorptive processes 
in the higher animals, particularly man, a direct comparison of these 
forms with plant life is of little value, although the economic consid- 
eration of safety in the handling of substances in commercial use is 
of great importance. 
A few general statements to indicate in a concrete form the differ- 
ences in behavior between the larger plant groups, as well as indi- 
vidual species, will illustrate the point which it is desired to make. 
It is unfortunate that the work of different authors can not, in 
many- instances, be directly compared, on account of differences 
in the method employed. However, much of value can be deduced 
from the few available examples. 
In his valuable work, Clark (3) calls clearly to the attention the 
variations among different species of molds. Certain toxic agents 
are shown to present great differences in this respect and others only 
slight ones. Even the stage of development of a single organism is 
of great importance, the conidia of the five species used proving more 
sensitive than the mycelium, so that the inhibition point for spore 
germination can not safely be considered as the toxic point for the 
development of mycelium. 
Other species of fungi, however, may behave differently from the 
ones Clark worked with, for Rumbold (25, p. 431) has recently shown 
that the ascospores and conidia of the blue-stain fungus (Ceratosto- 
mella sp.) are more resistant than the mycelium to sodium hydroxid 
and sodium carbonate. 
Another interesting phase of the question has been studied by 
Pulst (23). This investigator shows that the common green mold 
(Penicillium glaucum) has the power of gradually increasing its 
resistance to toxic agents. He claims that the individual itself 
without change of generation, but after a somewhat longer period of 
time, works up its resistance to copper sulphate to a high degree. 
He also shows by experiment that spores sown from generation to 
generation on progressively increasing concentrations of this salt 
likewise attain greatly increased resistance. Similarly, this newly 
developed resistance is evidenced by an increased rate of growth. 
For instance, when spores produced on a 3.2 per cent solution of 
copper sulphate are transferred to new media of like concentration, 
the mold will fruit again in about 10 days, while spores obtained from 
a culture containing no toxic substance and transferred in exactly 
the same manner require more than three months to reach the same 
stage of development. 
