34 Lewis Knudson 



of the flask, which increased the rate of photosynthesis and consequently 

 produced a more nearly normal plant. In all the other cultures it is 

 probable (see page 20) that the carbon dioxide content of the vessels 

 was lower than the normal, due to the decreased rate of diffusion through 

 the cotton stoppers. 



Another interesting observation was made in one of the lactose cultures. 

 The seed germinated, and the cotyledons increased in size to about 

 1 centimeter in diameter and then turned yellow. Increase in size con- 

 tinued until finally a root 1 centimeter in length and 0.5 centimeter in 

 diameter was developed. It appears that in this case the radish behaved 

 as a saprophyte. 



In two of the maltose cultures not included in the table, the leaves, 

 instead of being compound, were simple, narrow, and much elongated, 

 which is suggestive of certain morphological modifications obtained by 

 MoUiard (1907). 



EXPERIMENTS WITH WINTER VETCH (VICIA VILLOSA ROTH) 



Winter vetch was selected for the more detailed studies of the influence 

 of the different sugars on plant growth. This plant was chosen because 

 of the ease of obtaining uniform seed, the ease of handling, the lack in the 

 seed of a very large reserve, and the resistance of the seed to the steriliz- 

 ing agent. Furthermore, the plant is one that grows rapidly, and in its 

 early seedling stage is possessed of an anthocyanin pigment. 



INFLUENCE OF CERTAIN DISACCHARIDES ON GROWTH 



In the experiment to determine the influence of certain disaccharides 

 on growth the large cylinders were used as culture chambers. Each 

 cylinder contained 500 cubic centimeters of the nutrient solution plus 

 1.2 per cent of agar and the sugar to be tested. The seeds selected were 

 uniform in character and of an average dry weight of 30 milligrams, the 

 variation in weight being 2 milligrams. The seeds were sterilized by 

 immersion in the calcium hypochlorite solution for nine hours. One series 

 of cultures was maintained in the dark, and a second series was maintained 

 in the greenhouse. The former cultures were grown in the laboratory 

 at an average temperature of 23° C. The results of the experiment on 

 cultures kept in the dark are summarized in table 12: 



