662 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 2 



been sterilized by the method described. The plants were 

 grown for a period of twenty-five days and then data taken 

 on the various cultures. The various cultures are shown in 

 pi. 22 fig. 1. The galactose plants are separately shown in 

 pi. 22 fig. 5 and the detailed data are given in table i. 



An examination of the table reveals the fact that every 

 sugar acted beneficially except galactose. If the plants had 

 been examined a month later (as was the case with other cul- 

 tures), much greater differences would have been secured 

 between the check cultures and the susrar-containin 



& «.i VUlll-UllllIlf, 



Lactose is undoubtedly utilized by Canada field pea as well as 

 by vetch and probably before assimilation is converted into 

 glucose and galactose. Raffinose, which is also utilized, yields 

 on hydrolysis first levulose and melibiose, and the latter is 

 further transformed to galactose and dextrose. In the light 

 of the foregoing, it would appear from the results secured with 

 lactose and raffinose that levulose and glucose must exert 

 some protective action against the injurious action of 

 galactose. 



Influence of concentration of galactose. — In all of the pre- 

 vious experiments the galactose sugar was employed at only 

 two concentrations, namely, 0.2 per cent and 2 per cent. In 



following experiment a series of cultures was made 



concentrations: 0.125 



t> t> 



following 



h" 1 """^ ^"6 



cent, 0.25 per cent, 0.50 per cent, 1.0 per cent, 2.0 per cent, and 

 control cultures lacking galactose. The plants were grown in 

 large test-tubes 30 cm. X 4 cm., containing 50 cc. of the 

 nutrient medium plus 1 per cent agar. The galactose 

 employed in this experiment was provided by Dr. C. S. Hud 

 son 1 , Chief of the Carbohydrate Laboratory, U. S. Bureau of 

 Chemistry. The galactose sugar provided had been recrystal- 

 lized and was stated by Dr. Hudson to be of a very high degree 

 of purity and probably purer than any which could be secured 



market 



d with cotton and 



sterilized in an autoclave at 15 pounds pressure for a period 

 of 20 minutes. One pea was sown in each tube and the cul- 



1 The writer gratefully acknowledges his indebtedness to Dr. Hudson for the 

 galactose furnished. 



