IQtI} BRIGGS & SHANTZ—SOIL MOISTURE 213 
In the case of monocotyledons, we have found that the wax 
seal can best be added immediately after planting the seeds. On 
germination, these plants will grow readily through the wax, which 
forms a perfect seal around the stems (fig. 1). With dicotyledons 
it is advisable to keep the pets in a moist chamber, to reduce 
evaporation until the seedlings appear above the ground, when 
the wax seal can be applied without injury to the plants. 
Even in the case of dicotyledons, this 
wax seal is often applied at the time of 
planting. This prevents the soil from 
drying out between the time of planting 
and complete germination. Plants which 
do not raise the cotyledons above the soil 
surface and those with very small seeds 
often push through the wax without break- 
ing the seal. Other dicotyledons push their 
way through the wax cover without any 
difficulty, although it is necessary to reseal 
these pots after the seedlings are all up, ee 
especially in the case of plants with large Fic. 1.—Showing the 
cotyledons, such as the bean, squash, cu- aX seal on the surface of 
cumber, etc. 
Aeration, when necessary, can readily growing through the seal; 
be accomplished by making two small holes the wax was apple ma 
tough the wax to the bottom of the pot casieege after planting the 
0n opposite sides. A glass tube drawn to : 
a small opening and connected with a wash bottle is forced into 
me hole to supply moist air, and a similar glass tube is forced 
Into the opposite opening and attached to an aspirator to withdraw 
the air from the pot. The wax forms a perfect seal around the 
glass tubes. In this way many pots can be aerated and the holes 
tesealed with a hot wire in a comparatively short time. 
The wax seal method is also particularly adapted to the study 
of transpiration, since all loss of water is avoided except through 
the plant tissues. ; 
4. Serious fluctuations in temperature can be avoided by im- 
Mersing the pots to within 5 mm. of the top ina tank, preferably one 
through which a small stream of tap water is constantly flowing. 
