28 



Research Bulletin Ni 



suggested by Hasselbring (14) was followed. Erlenmeyer flasks 

 of 200 cc. capacity were used with 50 cc. of solution per flask. The 

 solutions in the flasks were autoclaved for 10 minutes at 7 lb. 

 pressure, and then inoculated by means of sterile pipettes with a 

 drop or two of spore suspension. The cultures were killed by 

 adding 10 cc. of 10 per cent HC1 to each flask. The cultures 

 were then filtered off on tared Gooch crucibles prepared with 

 asbestos, washed until acid free, and brought to constant weight in 

 a Freas electric oven at 100 C, and the dry weight determined. 

 It was found impossible at limes to tiller luxuriant cultures of 

 F. oxysporum by this method, because of the tenacity with which 

 this organism holds water. Consequently they were filtered on 

 -oit idler paper, transferred to tared Gooch crucibles, dried, ami 

 weighed The other organism holds water with little tenacity and 

 filters with ease. 



In all of experiments given below the following stock mineral 

 solution was used: 20 gm. \'II ( X<>.. ; 10 gm. KH 2 P0 4 ; 5,gm. 

 MgS0 4 per 1C00 cc. I !.,<>. When carbohydrates were employed, 



TABLE I 



Dry weight (in milligrams) after 20 days' growth in potato extract 



medium; room temperature 



FUSARIUM OXYSPORUM 



Temperature 



FUSARIUM TRICHOTHECIOIDE 



Temperature 



35° 



Flask 1 

 Flask 2 

 Flask 3 



Average 



60 



64 

 65 

 63 



87 

 100 

 147 

 111 



l°.ll* 



Kor 20 days no growth . i hen at 25 < '. for 25 days 



