THE POTATO TUBER. 
67 
The treatment of sets in the manner described with 
one or other of the substances used evidently leads ulti- 
mately to smaller percentage losses of weight than in the 
case of the untreated controls. The object of dressing 
“ cut sets ” with substances like those used in these ex- 
periments is to induce the more speedy formation of a 
protective covering of wound cork. This, as an examination 
of the percentage losses of weight in the above tables in- 
dicates, is evidently what happens during the earlier intervals 
of the entire period of exposure we find the losses of weight 
by the treated tuber sets are less than those of the un- 
treated sets, and in addition the fact is shown that of the 
three substances used, air-slaked lime functions best. It 
will be evident from a survey of the results given that 
the comparative loss of weight by treated and untreated 
sets must vary with the kind of tuber and the conditions 
of experiment selected. Under comparatively low tempera- 
ture conditions and in the absence of rapidly moving air 
currents, in other words, under conditions unfavourable to 
rapid dessication, the results vielded by tubers of the same 
kind as those used in Experiments 5 to 8 show the relativ- 
percentage losses of weight after 168 hours’ exposure to 
be 16.67%, 17.11%. r8'35% and T9. 01% respectively for 
lime, sulphur, sand and untreated tubers. Such condi- 
tions, however, do not always obtain in practice, and the 
fact remains that loss of weight by untreated sets is still 
in excess of that by treated sets. That the resultant smaller 
losses in the case of lime dressed sets is not due to the 
greater formation of wound cork is rendered probable by 
the following experimental facts : — 
In another series of experiments similarly established 
to the foregoing, determinations were made of the weight 
of wound cork formed ; these, expressed as percentages on 
the original weights of the material taken were 2.21%,, 
T.9%, 2.7%, and 2.83% for the lime, sulphur, sand and 
untreated sets respectively. Considering the nature of the 
material dealt with, these values do not differ greatly, and 
the view may be advanced that the efficiency of the various 
dressings depends primarily on the rapidity with which the 
induced formation of wound cork is conditioned by their 
use. The results of these experiments are not devoid of 
practical interest. We have the fact that under ordinary 
circumstances cut sets lose weight, which it is true may show 
considerable variation, and this increases with the ex- 
tension of the interval between preparation and planting. 
Such losses are certainly not favorable to the vitality of 
the buds of the tuber. On the contrary, there is really every 
reason w hy the freshly exposed surface of the cut set should 
