(VoL. 5 
156 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
iron arm about 16 inches from the free end, with turnbuckles 
interposed, took up the strain on the arms resulting from 
heavy plants on the platforms. 
One of the platforms, in addition to the brass sprocket be- 
low, had a second sprocket 4 inches in diameter, screwed to 
the latter. This second sprocket was connected by a link 
chain to the sprocket of the collar serewed to the central steel 
axis. A steel ladder chain running around the outer teeth of 
each platform sprocket completed the table proper. 
The apparatus was then connected up, by means of a re- 
ducing gear attached to the shaft of a 4-horsepower motor 
and an intermediate series of sprockets and chains for fur- 
ther reduction of speed, with the large sprocket wheel below 
the central plate of the table. As the whole table turned on 
its axis, and the small sprocket screwed to the central steel 
shaft remained stationary, this resulted in a movement of 
the link chain connecting this shaft sprocket to the second 
one on one of the plant platforms; in consequence, this plat- 
form turned slowly on its axis, and by means of the ring of 
the ladder chain transmitted the revolution to the other plat- 
forms. 
The table as a whole revolved about once every 45 seconds 
and each plant platform about once every minute. Wherever 
necessary, the sag of the chains was taken up by supporting 
them with fiber rollers. 
Without exception the experiments were carried out in the 
greenhouse, and the potted plants used had in all instances 
been grown under approximately similar conditions and then 
well accustomed to the environment of the experimental sec- 
tion of the greenhouse. Before being used in the experiments 
all exposed portions of every pot were coated with paraffin 
or wax seal. A thistle tube for watering and a bent tube for 
the release of air pressure were inserted into the soil, and the 
pot was sufficiently watered before.the soil was likewise cov- 
ered with the seal. When placed upon the platform of the 
rotating table each pot rested upon a saucer. The use of the 
rotating table made it somewhat inconvenient to employ any 
type of auto-irrigator, or constant moisture device, though 
