1915] 



KNUDSON TOXICITY OF GALACTOSE 



661 



Experiment with Canada field pea (Pisum sativum). — In 

 the first experiment with the pea the large cylinders were 

 again employed and to each were added 200 cc. of the nutrient 

 solution plus 1 per cent agar and the sugar whose effect was 

 to be tested. Cultures were made with raffinose, saccharose, 

 lactose, glucose, and galactose (" Merck's Highest Purity"), 

 the concentration of the sugar employed in each case being 

 2 per cent. The cylinders were fitted with cotton plugs as in 

 the previous experiment and then sterilized for a period of 

 one hour. In each cylinder were sown four peas which had 



TABLE I 



DATA ON CANADA FIELD PEA 

 (Duration 25 days. Taken February 13) 



Culture 



Glucose 



Lactose 



*Raffinose 



Saccharose 



Check 



Maltose 



Galactose 



No. 



of 



plants 



3 



4 



4 



Height 



of 



plants 



cm. 



Total 



green 



wt. 



grams 





44 

 40 



38 



40 

 40 



33 

 33 



4 



3 



4 



32 

 33 

 24 

 33 



6.250 



Dry 



wt. 



coty- 

 ledons 

 grams 



.155 



6.700 



.169 



6.500 



39 



35 

 36 

 35 



32 

 23 

 34 



33 

 40 

 34 



28 



7.600 



4.450 



.192 



.160 



.150 



Dry 



wt. 



roots 



grams 



.170 



105 



.130 



.144 



Dry 



Total 



wt. 



dry 



tops 



wt. 



grams 



grams 



.364 



.689 



Av. 



dry 



wt. 

 grams 



.229 



355 



.328 



.629 



.650 



.157 



.162 



.430 



.734 



.075 



.190 



6.600 



.222 



.142 



.386 



.415 



.183 



.138 



Gain 



per 



plant 



grams 



+ .085 



+ .007 



+ .012 



+ .036 



.012 



.750 .187 



+ .034 



Plants small and roots injured. (See pi. 22, figs, la and 5.) 



* Reducing sugar formed in medium probably as a result of secretion of invertase 

 and raffinase from roots. Acidity of entire medium at time of examination equiva- 

 lent to 0.7 cc. N/10 KOH. 





