Experiments on Sprouting Potatoes in Gas Mixtures. 240 
Results. Three series of experiments were carried out. (1) The 
influence of oxygen and of carbon dioxide upon sprout formation 
were simultaneously tested, the following twelve mixtures being 
used :—5%, 10%, and 20% oxygen combined respectively with 0%C0 2 
10% C0 2 , 20% C0 2 , and 40% C0 2 , (Table 1 and 2). The influence of 
oxygen alone was tested in the following concentrations:—5%, 10%, 
20%, 50% and 80% (Tables 3, 4 and 5). 
Carbon dioxide at a concentration in the atmosphere of 20% 
or higher inhibited sprouting. Carbon dioxide in a 10% concen¬ 
tration greatly reduced the number of sprouts formed and also 
reduced to a less degree the size of the sprouts that appeared, that 
is, their rate of growth. The retarding and inhibiting action of 
carbon dioxide was not markedly influenced by the amount of 
oxygen present as far as tested, i.e., between 5% and 20% oxygen. 
Injury and death occurred after 6-7 weeks in 40% carbon dioxide. 
This injury was accelerated by oxygen concentrations above a certain 
minimum in proportion to the amount of oxygen present. It 
occurred more quickly where 20% oxygen was present, in conjunction 
with COjj, than where 10% was present, and more quickly in this case 
again than where only 5% was present. 
In the case of 10% and 25% carbon dioxide no injurious effect 
was shown during the two months the potatoes were in the 
presence of the artificial gas mixtures, but subsequently the sprouting 
did not return to its normal value, and rotting set in earlier than 
with the controls. This premature rotting was most pronounced in 
the potatoes which had been in 20% oxygen, and least in those from 
5% oxygen. It appears, therefore, that oxygen becomes harmful 
to the potato in concentrations above 5—10%, and that this harmful 
action is increased in proportion to the amount of oxygen present. 
The results of the experiments in which the effect of different 
oxygen concentrations (in the absence of C0 2 ) was tested supports 
this conclusion (Tables 3 and 4). In concentrations above 20% oxygen 
clearly depressed sprouting. The number of sprouts produced was 
fewer and the size smaller. The effect became more marked 
in higher concentrations of oxygen. A concentration of 50% 
oxygen caused injury in 4 to 5 weeks. Cell death occurred in 
localised areas, and moulds became established. A concentration 
of 80% killed the potatoes in the same period. A decrease in oxygen 
concentration below 20% did not lessen sprouting. On the contrary 
the optimal concentration for sprouting appeared to be 10% or even 
5% oxygen. 
After the middle of June the natural sprouting capacity of the 
potatoes fell off regularly from week to week (Table 6). 
