60 



Lewis Knudson 



Pfeffer's solution plus 1 per cent of agar, to which was added the sugar or 

 sugars to be tested. Canada field pea was again employed and all cultures 

 were made in triplicate. Two plants were grown in each culture. The 

 plants were grown in the laboratory and not in direct light. The experi- 

 ment was started on October 25, 1915, and completed on November ?3, the 

 duration being twenty-nine days. The concentration of galactose was con- 

 stant, each of the cultures being of 0.05 molecular solution. The concen- 

 trations of glucose varied. The different combinations and the results 

 are given in table 25, and other results are shown also in figure 11. 



TABLE 25. Antagonistic Action of Glucose Toward Galactose 

 (Duration, twenty-nine days) 



Nutrient medium 

 contains 



Culture 

 number 



Appearance of roots 



Average 

 length of 

 primary 

 root 

 (centi- 

 meters) 



Galactose, 

 Glucose, 



Galactose, 

 Glucose, 



Galactose, 

 Glucose, 



Galactose, 

 Glucose, 



Galactose, 

 Glucose, 



Galactose, 

 Glucose, 



0.05 mol. 

 0.20 mol. 



0.05 mol. 

 0.10 mol. 



0.05 mol. 

 0.05 mol. 



1 

 2 

 3 



4 



5 



I 6 



7 



0.05 mol.. 

 0.025 mol. 



0.05 mol.. . 

 0.0125 mol. 



0.05 mol.. .. 

 0.00625 mol. 



Check (no sugar) 



10 

 11 

 12 

 13 



14 

 15 

 16 

 17 



118 

 19 

 20 



Long, slender 



White, slender 



White, slender 



White, slender 



White, slender 



White, slender 



SHghtly brownish 



Slightly brownish 



Shghtly brownish 



Brownish 



Brownish, no penetration,* dead. 

 Brownish, no penetration, dead . 



9.0 

 9.0 



13.0 

 9.0 

 9.0 



10.0 

 6.0 

 7.0 

 9.0 

 2.5 



No penetration of agar. All roots in 

 contact with medium killed 



Long, slender, white. 



10.0 

 9.0 



* " No penetration " means that the roots do not grow into the agar. 



The rather interesting result is noted that the antidotal influence of 

 yfucosn is effectively attained only when the glucose is at a concentration 

 greater than that of the galactose, although marked depoisoning action is 



