Loss of Moisture from Winter Twigs. 11 
in a living-room, where the readings could be 
taken at frequent intervals. It will be noticed 
that the rate of evaporation was nearly constant, 
averaging about one-half a centigram per hour: 
Addi- 
Lost] tional) In | In | In| In | In | In | In | In] In | In | In } To-]| Per 
in loss 18 | 24 | 26 | 36 | 44 | 48 | 5x | 60 | 64 | 68 | 77 | tal | cent 
2hrs} in zz} hrs| hrs | hrs | hrs| hrs] hrs| hrs| hrs| hrs | hrs | hrs | loss | loss 
hrs 
Twig 
. weighing 
4.425 Hs 275 2 5 | 4 2) 2 4} 2 2/3 | 39 8.8 
grams. | cg.| °°8- | eg. | eg.| eg. eg.| eg.| eg. | cg. | eg. | eg. | eg. | eg. | eg. 
It has been said that the rate of the loss of 
moisture from trees in winter determines the rela- 
tive hardiness of different varieties of apples, and 
of some other fruits; and similar inferences have 
been made respecting the ability of foliage to endure 
summer droughts. The following table shows studies 
of twigs of varieties of different degrees of hardi- 
ness, but it will be seen that the per cent of loss 
of moisture bears no relation to the supposed 
hardiness of the varieties. 
Early in April, twigs from the previous year’s 
growth were taken from several varieties of apples, 
which vary much in their ability to endure our cli- 
mate (those marked by asterisks being supposed to 
be the hardiest varieties). The twigs were carefully 
weighed, and the cut ends were then sealed with 
wax to prevent evaporation only through the bark. 
At the expiration of two days the wax was re- 
moved and the twigs were again weighed. The 
twigs were kept in an open shed: 
