14 
Colorado Experiaient Station 
were dug caused some frost injury which resulted in losses in weight 
in addition to the sources enumerated above. 
The potatoes were placed in the storage cellar and the field 
weights obtained the day on which they were dug. The sorting was 
done during the winter, usually between the middle of December and 
the middle of February, after which the cellar weights were re- 
corded. As soon as the potatoes were placed in storage the tempera- 
ture of the cellar was lowered as rapidly as possible until a uniform 
temperature slightly below 40 degrees F. was reached. The ther- 
mograph charts show that during the fall and winter seasons covered 
by the experiments a temperature range within the limits of 34 to 
40 degrees F. was maintained from the last of November to the last 
of March. The relative humidity fluctuated betAveen 80 and 90 per 
cent, depending upon the frequency of ventilation, except that for 
short periods when the ventilators Avere open, percentages beloAv 
60 were sometimes reached. 
During the years 1915, 1916 and 1918, Avhen there aa^s practically 
no field frost, the average losses during the storage period Avere very 
uniform. varying only from 7.0 to 7.8 per cent. The greater average 
loss in 1917, 9.1 per cent, is attributed largely to the effect of frost 
injury befoTe digging in the case of some of the late varieties, par- 
ticularly the Pearl. While the per cent of frosted tubers Avas com- 
paratively small the loss in AA^eight from those Avhich Avere damaged 
was considerable. The AAude variation in losses from the different 
varieties during a given season does not necessarily indicate that 
the magnitude of the loss may be a varietal characteristic tho the 
losses may be associated Avith certain relations of the variety to 
conditions. For example, the relatively small losses of the early 
varieties may be explained by the fact that they Avere dug early in 
the season, usually Avhen the ground AArns dry so that practically no 
dirt adhered to them. The Pearl, as groAvn on the comparatively 
heavy soil of the station farm, produces a large percentage of 
knobbed tubers Avhich carry more dirt into the cellar than the 
smooth tubers of the Rural NeAv Yorker. In 1917 three of the 
varieties, Charles Downing, Late Ohio and Irish Cobbler, Avere not 
only almost entirely free from dirt AAdien dug but Avere sorted and 
the cellar weights obtained the second day aftei* digging thus af- 
fording little opportunity for loss from this source. On the other 
hand in 1916 the digging of the Pearl and Rural NeAV Yorker aauis 
delayed by rains until it Avas so late that no time could be alloAA'ed for 
the ground to dry out, consequently the tubers and the soil adher- 
