44 



Mycologia 



to remove all the tannin. After a certain time all of the fungi 

 made their way through the cork films and infected the agar 

 below. However, if such cork sheets were allowed to absorb 

 tannin solutions and were then inoculated as before, the fungi 

 were not able to penetrate the cork at all. It might be added that 

 it was early observed that commercial tannin is slightly more toxic 

 than the fresh extract of oak bark. All of these facts taken with 

 the observations of others led the authors to believe that the 

 presence of tannin in the host cells may often help to produce an 

 immunity from the attacks of fungi. — E. D. Clark. 



