Feb. 3,1923 Use of AIternating Temperatures in Seed Germination 315 
GERMINATING CHAMBERS 
All of the germination tests were made in copper chambers surrounded, 
except the door, by a water-jacket space, the water in this space being 
the medium of temperature control. Figure 11 shows one of the cham¬ 
bers in median vertical section. 
The interior space of each germinating chamber is approximatelyja 
20-inch cube. A pan of water (a) in the bottom of this space maintains 
a nearly saturated atmosphere in the chamber. At intervals of 2 inches 
on the sides of the chamber are copper ledges (b) for the reception of 
perforated copper trays (c) which carry the seeds and which in the figure 
/ 
2 
3 
4 
5 
6 
7 
8 
9 
/O 
// 
/2 
Fig. 12.—Diagram of a seed tray with folded blotters. The blotters are numbered from i to 12. 
are numbered from i to 8, beginning at the top. The gas for heating the 
chamber passes through the thermo-regulator (d), which is inserted in 
the water jacket (e) and thence to the burner (/). The water for cooling 
the chamber enters the water jacket through the rubber tube (g) and the 
perforated copper sheet ( h ). The overflow passes out through the waste 
pipe (i). Whenever necessary, ice was placed in the ice box (k) and the 
water passed over it before entering the water jacket. The thermometer 
(/) indicates the temperature of the air in the extreme top of the chamber. 
Each seed tray except No. 8, on which bluegrass seed was tested with 
the use of the Jacobson apparatus, received 12 folded blotters (4 thick¬ 
nesses) for the small seeds, which were tested on top of blotters, and 24 
(8 thicknesses) for the larger seeds, which were tested between blotters 
in duplicates placed on top of each other. Figure 12 shows the arrange¬ 
ment of the blotters upon a seed tray. 
