64 . Lewis Knudson 



was retarded. The retardation of transpiration would of course decrease 

 the absorption of sugar, since the sugar would not be rapidly removed 

 from the zone of absorption owing to the lack of a rapidly ascending 

 current of water. This would account partially also for the great influence 

 of the sugar on root gi'owth. 



Special attention should be called to this very marked influence of 

 saccharose, maltose, glucose, and fructose on root gro-s\i;h. In the presence 

 of one of these sugars a very much-branched root system developed, 

 the influence of the sugar on the root growth usually becoming e\adent 

 within two weeks. Those plants grown in the absence of sugar, on the 

 other hand, usually showed roots only shghtly branched. It would 

 appear that the sugar absorbed by the plant is largely utihzed in the 

 root itseK, and perhaps there is but slight migration of the sugar to the 

 stems and leaves of the plant. This would probably result in a lessening 

 of the downward migration of the sugar, a consequence of which would 

 be increased top growth. So very evident to the naked eye is the favorable 

 influence of sugars on the root growth that one is inclined to consider 

 the root as being partially saprophytic. (Fig. 6, page 43.) 



Special attention should be called also to the abihty of radish, vetch, 

 and Canada fleld pea to utilize the sugar lactose. This sugar has not 

 been found in the plant kingdom. The enzyme lactase has been found 

 in but relatively few seeds of higher plants (Czapek, 1905), yet the sugar 

 is used in demonstrable quantities and is apparently assimilated. This 

 being the case, there must be a production of the enzyme lactase in response 

 to the sugar lactose, and another case of the production of a quahtatively 

 regulated enzyme may here occur. 



Surprising also is the toxicity of the sugar galactose for the green plants 

 when it is considered that it is utilized by various fungi and when its 

 close similarity to glucose is recalled. Galactose differs structurally 

 from glucose in that the positions of the and OH radicals are reversed 

 in the third asjTiunetric carbon. 



Maze and Terrier (1904) noted a loss of chlorophyll when glucose 

 was supplied to corn, and Servettaz (1913) found the same condition 

 for moss. These investigators consider that there is a loss of chlorophyll 

 when its function is not necessary. It is more probable that the loss 

 of chlorophyll is due to the changes resulting in the nutrient solution, 

 as, for example, an unbalanced condition or the precipitation of the iron 



