64 
A. STOWARD, D.SC. : 
Table I. 
Comparative losses of weight by mutilated and 
unmutilated tubers. 
Alter hours 
Peeled tubers 
Eye-exercised tubers Intact tubers 
24 
24.24% 14.02% 
2.22 
2.42% 
48 
31.87 22.4 
4-05 
4.29 
72 
34.13 28.35 
4-79 
4-74 
0.11% 
0.10% 
96 
35.21 32.29 
5 -i 9 
5.20 
0.17 
0.13 
120 
5-25 
5-49 
0.29 
0.23 
I44 
43-56 38.06 
0-35 
0.30 
168 
47.O 41.O 
5 - 9 8 
6.03 
0.48 
0-39 
A glance at these results will show how considerable 
is the loss of weight by mutilated tubers as compared with 
intact tubers. Generally speaking, at any selected stage 
of the experiment the magnitude of these losses follows 
in descending order the direction — peeled tubers, eye- 
excised tubers, intact tubers — as, in fact, anticipation 
would lead one to suppose. If now we turn to consider 
the relative losses of weight after a period of 168 hours the 
results are striking. In the experiments under consideration 
these are 41-47%, or nearly half, the original weight for 
peeled tubers, 5.98-6.03% or slightly more than i/20t.h for 
eye-excised tubers, and 0.48-0.4% or i/25oth foi intact 
tubers. These values alone strongly support the sup- 
position already foreshadowed by histological observations, 
that one of the functions of the skin is to prevent rapid 
dessication of the tuber. Its removal, 01 even paitial 
removal, in the case of eye-excised tubers, as these data show, 
leads to losses of weight which are greatly in excess of those 
lost by intact tubers. Such apparent irregularities as are 
shown in the rate at which loss of weight ensues in the 
case of peeled tubers are in part to be attributed to vari- 
ability in the area of surface exposed, in part to other 
deeper-seated and less evident causes. 
At the outset we must guard against the supposition 
that these weight-losses are due entirely to losses of moisture 
by the objects under investigation. In the case of peeled 
and bucl-exciscd tubers other factors require recognition ; 
the chief of which is the increased respiratory activrty 
consequent upon mutilation of the tubers. In the case of 
intact tubers the loss of weight recorded in 1 able 1 are chiefly 
due to the excretion of carbon-dioxide ; in other words, 
to the respiratory activity of the tuber. We may legiti- 
mately suppose that the values given represent roughly the 
daily loss due to normal respiration. The unsprouted 
tuber is alive, but it is in a quiescent vital condition. 
