TOCHINAI : STUDIES ON THE PHYSIOLOGY OF Fusariimi Ulli. 3 1 



iKited spores immediately formed chlamydospores. 



If sucli a shrunken spore was sown in a nutrient solution, it did not 

 germinate at all. 



From the results of these tannic acid cultures, the following conclusions 

 may be drawn : 



1. This fungus can not assimilate tannin even to a slight degree as 

 food material, and its hyphal growth is retarded proportionately according 

 to the degree of the concentration of tannin. 



2. When the concentration of tannin becomes more than \%, the 

 hj-phal growth of the fungus is almost prevented. 



3. In tannin solutions of over 1% concentration the germination of the 

 conidia is retarded heavily and many of the spores are killed. 



4. But even 2)% concentration of tannin is not fatal to this fungus. 

 The conidia can still germinate and produce chlamydospores. Moreover the 

 fungus which was kept in this solution for three weeks, has maintained its 

 vitality. 



5. Tannin retards the growth of the fungus and thereby causes the 

 formation of the resting spores. 



HI. Citric acid culture 



After the experiments with tannic acid cultures, I undertook to investigate, 

 whether or not tannic acid has special effect in preventing the attack of the 

 fungus, compared with other acids which are generally found in the plant- 

 body. I have used citric acid for the comparison, as it is ordinarily used 

 for such experiments. For the standard nutrient solution, both the synthetic 

 solution as in the preceding formula, and potato decoction hard agar were 

 used, in order to show what influences of standard nutritive media may have 

 on the relation Ijetweei^ the growth of fungus and toxicity of chemicals. 



Experiment i. 



Cultural media were prepared as in the case of tannic acid cultures. 

 They were inoculated and incubated at 25^C. Four cultures were used for 

 each percentage. The percentages and results are shown in following table. 



