BUTLER: SUGAR IN TUBERS OF SOLANUM TUBEROSUM 115 
Bell jar no. 2 contained 1,936 grams of potatoes and was 
connected with a water siphon by means of which approximately 
8 per cent of the volume of the contained air was renewed daily. 
Bell jar no. 3 contained 1,897 grams of potatoes and was 
connected with a water siphon by means of which approximately 
0.8 per cent of the volume of the contained air was renewed daily. 
Within a few days the air in all the bell jars became saturated 
with water vapor. The experiment was discontinued after 90 
days, when the potatoes in the different bell jars were analyzed 
and found to contain siigar as follows: 
Bell jar no. I, 0.09 per cent sugar; bell jar no. 2, 0.22 per cent 
sugar; bell jar no. 3, 0.66 per cent sugar. The effect of reducing 
the oxygen supply on the accumulation of sugar in potatoes is, 
therefore, quite marked, though not nearly so notable as that of 
low temperature. 
II 
The view is very generally held that sugar accumulates in 
potatoes at the time of germination and that this accumulation is 
essential thereto. According to de Vries* sugar begins to appear 
in potatoes just prior to germination but before the buds show 
any signs of growth. Resting potatoes, he says, contain for the 
most part no sugar, its appearance indicating the initial stages of 
germination. The sugar first appears in the neighborhood of the 
eyes, more precisely in the parenchymatous tissue surrounding 
the bundles leading to them. At first present in small amounts, 
it soon increases in quantity, developing in all parts of the tubers. 
During their early period of growth the shoots contain starch but 
no sugar, though the tubers themselves are full of the latter, the 
larger amount being in the medulla, the smaller in the cortex. 
When the shoots are 8 mm. long sugar is found in them only in 
isolated spots, but somewhat later it is generally distributed, and 
this condition remains unchanged until they come through the 
“soil. 
The accumulation of sugar in potatoes has not, however, as 
regards germination, any particular physiological significance. 
As in the case of resting potatoes the amount of sugar found in 
* Vries, H. de. Keimungsgeschichte der Kartoffelknollen. Landw. Jahrb. 7: 
236. 1878. : 
