Influence of Certain Carbohydrates on Green Plants 47 



Pfeffer's solution was used, with the addition of 1.2 per cent of agar 

 and the sugar to be tested. Control cultures lacking sugar were also 

 set up. In each culture vessel was placed 300 cubic centimeters of the 

 solution to be tested. The culture flask was then stoppered, and the 

 entire top of the vessel swathed with cotton and cheesecloth to prevent 

 the collection of spores or bacteria on the stoppers after sterilization of the 

 vessels and their contents in the autoclave. 



Eight separate lots of 100 seeds each, selected for uniformity, were 

 placed in weighing dishes and weighed. The water content was also 

 determined in sample lots. Into each of the weighing dishes, the capacity 

 of which was 25 cubic centimeters, 20 cubic centimeters of the calcium 

 hypochlorite solution was poured. The seeds were immersed for thirty-two 

 hours, after which each lot was transferred to the culture vessels, the 

 calcium hypochlorite solution being first poured off. 



The seeds were sown on June 16 and the first respiration determinations 

 were begun on June 17 at 11 a. m. The first weighings were made at 

 11 a. m. on June 18. Unfortunately the determinations for the first 

 few days, except in a few cases, were not accurate. This was due to 

 several causes — to leakage in some of the series, while in other cases the 

 water pumps were not properly regulated. Beginning with June 20, 

 however, the entire apparatus was in good working order, and the results 

 from that date are consistent and accurate in so far as this type of apparatus 

 will permit. It is seen in table 18, in which the results of the experiment 

 are given, that by June 20 the sugar cultures showed greater evolution of 

 carbon dioxide than did the check cultures. Individual cultures may show 

 slight variation, but this is to be expected since a slight variation in 

 growth, as regards both root and top development, may occur in the 

 different gro^^i:h chambers. The total carbon dioxide evolution in the 

 duplicate cultures are in very close agreement. 



The order in which the cultures are given in table 18 indicates the relative 

 positions occupied by them in the experiment. Those at the right side 

 of the table were slightly favored because of having a slightly better light 

 exposure. This accounts for the greater increase in carbon dioxide of check 

 culture 2 as compared with check culture 1, or of glucose culture 1 as com- 

 pared with glucose culture 2. The maltose culture 2 became contaminated 

 with a mold, and consequently the data are of little value except as a 

 check on maltose culture 1 during the earlier stages of the experiment. 



