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. 



