TOCHINAI : STUDIES ON THE I'HVSIOI.OGV OF Fusarintn Ulli. 27 



duct of metabolism or is produced by the irritation of parasitic organisms 

 without any ecological meaning. \Ve must consider about the physiology of 

 tannin formation instead of trj'ing to imagine its ecological meaning. 



Experiment i. 



The effects of tannic acid on the h>-phal growth of the fungus. 



For standard medium I have used a solution having the following formula. 

 Ammonium nitrate NH^NO:, lO.O g. 



Potassium biphosphate KJ-LPOj 50 g 



Magnesium sulphate (cryst.) MgSOj 2.5 g. 



Cane sugar Ci.H.j.^Ou SO o g. 



Distilled water H..O 1 000.0 cc. 



Portions of the standard nutrient solution, 50 cc. each, were placed in 

 a number of Erlenmeyer's flasks. To these tannic acid was added in vary- 

 ing percentages, three flasks of each different percentage being prepared. 

 They were sterilized in Koch's steam sterilizer for half an hour twice with a 

 day interval, and inoculated with a bit of mycelium or conidia. If the spores 

 could easily be separated from the mycelium, the result would be more 

 accurate, but as it was very difficult to do, I have followed a simple method 

 of inoculating it with a mixture of the mycelium and conidia. Then incu- 

 bated them at 2 5°C., and after ten days compared their growth. 



(a) At first the cultures which contained tannin lower than 0,4% were 

 observed. To compare the degree of their growth I have adopted a method 

 of weighing their mycelium after ten days from inoculation. For this purpose 

 I put the filter papers in a desiccator and dryed them absolutely, and then 

 weighed ever>' one of them. Through these filter paper the cultures were 

 filtered, and after three or four times washing with distilled water the m>'cclium 

 retainetl in the filter paper as a packet. Evaporate the moisture of the 

 packets in a boiling hot water desiccator, and then kept them in a calcium 

 chloride desiccator for some days, and weighed them. By subtracting the 

 weights of the filter papers from the obtained weights of the packages, the 

 weight of the mycelium de\eloped in each culture was found. But in this 



