Annals 



of the 



Missouri Botanical Garden 



Vol. 2 NOVEMBER, 1915 No. 4 



TOXICITY OF GALACTOSE FOR CERTAIN OF THE 



HIGHER PLANTS 1 



LEWIS KNUDSON 

 Assistant Professor of Plant Physiology, Cornell University 



In the course of investigations upon the effect of sugars on 

 the growth of certain higher plants, the sugar galactose was 

 employed. In experiments with vetch (Vicia villosa) the 

 plants grown in the presence of 2 per cent galactose showed 

 very marked injury, the injury being especially manifest by 

 a killing of the roots and accompanied by a reduction in the 

 growth of tops. The results secured were the more surpris- 

 ing in view of the fact that lactose sugar employed coin- 

 cidently influenced beneficially the growth of the same plant. 

 Certain experiments were therefore made to determine 

 whether or not the effect of the galactose was consistent. 



Method of experimentation. — The plants were grown under 

 sterile conditions on agar media containing Pfeffer's nutrient 

 solution 2 of one-half its normal strength. This solution is 

 neutral in its reaction. The solution contained varying 

 amounts of galactose sugar, the source of which is indicated 

 in each case. 



1 The writer acknowledges gladly his indebtedness to the officers of the Mis- 

 souri Botanical Garden for facilities and courtesies extended to him during his 

 stay in St. Louis. 



2 CaN0 3 2 grams 



KNO3 0.5 grams 



KC1 . 25 grams 



K 2 HP0 4 0.50 grams 



MgS0 4 0.50 grams 



Fe 2 Cl 3 4 milligrams 



Dist. water 6 liters 



Ann. Mo. Eot. Gard., Vol. 2, 1915 



(659) 



