Jan. 13,1923 
New Respirometer for Seeds 
107 
seed container has to be omitted. These small apparatuses are so short 
that the seed containers can be handled by inserting an appropriate 
hook into the cut-out which receives the seeds, whereas in the larger 
apparatuses the ring at the top is necessary. 
The respiration apparatuses by themselves are hard to handle, so the 
carrier shown in median section in figure 2 was devised for use with any 
number up to eight at one time. Into threaded holes bored through a 
circular cast aluminum base (A) % inch thick and 9 inches in diameter 
are screwed nine posts, which consist of pieces of %-inch, heavy-walled 
brass tubing (B, B')- The tall central post (B) with the T connection 
serves as a handle, while to the other eight posts, covered with >£-inch 
thick-walled webb rubber tubing, the eight respiration apparatuses are 
bound with heavy rubber bands. A number of thicknesses of old rubber 
matting (C, C') appropriately placed, and all but the bottom one fur¬ 
nished with eight holes a little larger than the combined sizes of one of 
the brass posts and a respiration apparatus, hold the respirometers up¬ 
right and protect them from the breakage which might be caused by 
bumping on metal. 
The upper diaphragm of rubber matting (O') is stiffened by an under¬ 
lying diaphragm of sheet aluminum or other appropriate material (C") 
and is held at the proper height by short pieces of rubber tubing (D, D') 
on the brass posts. The holes in the bottom of the aluminum base are 
partially closed with small pure gum rubber tubing (E, E) and any one 
of the eight short hollow posts then serves for the reception of the ther¬ 
mometer (P). In case of fluctuations of temperature, this thermometer 
should not be depended upon to register the temperature of the water 
outside of the tubular post in which it is inserted. 
OPERATION OF THE APPARATUS 
The respiration tubes (fig. 1, A) having been provided with heavy 
rubber bands, the seed containers with their load of imbibed and sterilized 
seeds are lowered into place, and the contents of the apparatuses are 
rapidly aerated by drawing through each a strong current of air. The 
vasalined ground glass stoppers with the stopcocks opened and the 
caustic chambers unstoppered are rapidly put in place, forcing each down 
as far as it will go with a gentle twisting motion and placing them so that 
the bent delivery tubes (fig. 1, M) from the caustic chambers will deliver 
onto the closed side of the seed containers. As soon as its top is in place, 
each apparatus is bound to its post. The whole battery is now sub¬ 
merged in the water bath, so that the water covers the tops of the res¬ 
piration tubes, and the mercury is poured into these tops. As soon as 
the whole battery has come to the temperature of the water bath, which 
may be hastened by gently raising and lowering it, the stopcocks in the 
leveling tubes are closed, care being taken to see that the respirometers 
stand vertically and that the mercury is at the same level in the two arms 
of each manometer, the caustic chambers are stoppered, and the baro¬ 
metric pressure of the room is recorded. 
After an appropriate length of time, which will usually be not less than 
24 hours, from 1 to 3 cc. as required of 20 per cent sodium hydroxid 
(NaOH) is measured into each caustic chamber, leaving the stoppers 
out; the manometers are gently tapped to see that the mercury moves 
freely to its proper level; manometer readings are taken by holding a 
scale behind the manometer; the caustic is cautiously admitted into the 
