BUTLER: SUGAR IN TUBERS OF SOLANUM TUBEROSUM 111 
the following relation was approximately obtained, x being the 
amount of sugar formed at 0° 
pats” Cc, and at 6° C. 
He also observed that individual potatoes of the same variety 
showed marked variations in the rapidity with which sugar 
accumulated in their tissues, but that if at 0° C. sugar accumulated 
in relatively small amount in the tubers of a given variety, then 
no accumulation would occur at 6° C., and conversely, if sugar 
was formed rapidly at 0° C., then a temperature of 8° C. would be 
usually necessary to effect the same result. At 10° C. sugar never 
accumulated. 
The fact brought to light by Miiller-Thurgau that different 
varieties of potatoes exhibit differences in the rapidity of sugar 
accumulation is readily confirmed, as the following table shows. 
TABLE I 
SUGAR ACCUMULATION IN DIFFERENT VARIETIES OF POTATOES STORED AT 1°-5° C, 
FOR 28 DAYS 
Percentage reducing sugar in potatoes* 
At beginning of 
Variety of potato ” experimdnt After 28 days Daily increase 
ae ee way a 0.59 0.97 +0.013 
Piers WOME Se a site 0.88 0.85 —0.001 
Rural New Yorker.......... 0.17 I.01 +0.03 
Sips aceceia wiwias tee 6 De 0.15 r25 +0.039 
BOOTY Ose tecnico oe ee 0.42 0.86 +0.015 
Red Alconates vr hs vs 0.10 I.42 +0.047 
RBREY Ree eS San ies 0.43 1.10 +0.023 
BROW ICEOE oo toe Soars 0.53 1.22 +0.024 
PACE OIC 8p Cel nr ees 0.43 1.04 +0.021 
Miiller-Thurgau found, taking his results for 3° C., as these 
more nearly approach the average temperature at which the 
potatoes were stored in the above experiment, that the daily 
increase during a period of 30 days was 0.021 per cent, results which 
are of the same order as those given in the above table. 
According to Miiller-Thurgau sugar does not accumulate in 
resting potatoes when they are stored at a temperature of 8° C. 
* All the quantitative determinations given in this paper were kindly made for 
me by Mr. F. B. Morrison, Madison, Wis. : 
