1g11] TRANSEAU—APPARATUS FOR TRANSPIRATION 59 
this, but the plants appear to withstand the experimental conditions 
perfectly in this largest shell and not so perfectly in the more closely 
fitting ones. When the irrigators are used, it is convenient to have 
a 1 cm. hole in the side of the shell closed by a cork through which 
the air may be changed at intervals by means of a small bellows. 
This avoids the necessity of removing the roof from the shell during 
30 eu 
Average Ratio 1.08 
| See Ratio 137 \ ae | Soto Oe ‘ 
epee Ee SRE 
35 
3 a Ne "Average Ratio 133 
5 
1G. 5. Saeco from the average ratio between two synchronous records 
cilculated to 2-hour periods: A, two vaporimeters; B, two irrigated pelargoniums; 
C, two pelargoniums Sead at 24-hour intervals; average ele calculated from the 
total water losses. 
the experiment. The smaller pots are brought to the upper level 
of the shell by being placed on a strip of aluminum bent in the form 
ofaW. This raising of the pot above the level of the water reser- 
voir is necessary to prevent flooding of the soil. 
In constructing the graphs from the actual records and in cal- 
culating the ratios, an engineer’s slide rule has been found to be a 
great time saver. Fig. 4 shows the complete record for a portion 
of experiment 8. 
To determine to what extent two records may be expected to 
