A NEW AND EFFICIENT RESPIROMETER FOR SEEDS AND 
OTHER SMALL OBJECTS: DIRECTIONS FOR ITS USE 1 
By George T. Harrington, formerly Scientific Assistant , Seed-Testing Laboratories 
and William Crocker, formerly Plant Physiologist , Drug-Plant , Poisonous Plant , 
Physiological , awd Fermentation Investigations , Bureau of Plant Industry , United 
States Department of Agriculture 
PREVIOUS RESPIRATION APPARATUSES 
In the study of the dormancy, after-ripening, and germination of 
seeds, quantitative studies of their respiration are of major importance. 
For such studies on seeds and other small objects, a great many devices 
have been used, but none of them is perfectly adapted for the kind of 
studies the authors desired to make. Hence, the attempt to devise a 
new apparatus which would meet our requirements. Some of the appa¬ 
ratuses previously used, with their limitations, are indicated below. 
They are grouped according to the principle involved in the method. 
(i) DEVICES TOR ABSORBING WITH CAUSTIC THE CARBON DIOXID (CO a ) 
RESPIRED INTO A STREAM OF CO a -FREE AIR, OR OTHER GAS OR MIXTURE 
OF GASES, WHICH IS CONSTANTLY BEING DRAWN THROUGH THE APPA¬ 
RATUS CONTAINING THE RESPIRING MATERIAL WITH SUBSEQUENT 
DETERMINATION OF THE AMOUNT OF THIS ABSORBED C 0 2 BY TITRATION 
OR BY FILTERING AND WEIGHING THE CARBONATE 
Among the earliest, most widely known, and most generally used of 
these devices are the long inclined tubes first used by Pettenkofer ( 21 ),* 
and later somewhat modified by Pfeffer ( 22 ). These tubes, with or 
without modification, and combined with appropriate special devices 
for incubation of the experimental material, and for controlling the pres¬ 
sure when necessary, have been used by a large number of investigators 
in important studies on carbon assimilation and normal and intra¬ 
molecular respiration. Winkler’s modification in Hempel ( 11 ) of the 
Pettenkofer tube consists in bending it into the shape of a spiral so that 
it is easier to use. 
Other devices which have been much used for the absorption of C 0 3 
in a stream of air which had been drawn through the receptacle containing 
the respiring material consist of vertical towers of caustic solution. 
The tower invented by Reiset {23) has three multiperforate disks of plati¬ 
num inserted to interrupt the stream of air and break it up into small 
droplets, thus insuring complete removal of the C 0 2 . Reiset tubes have 
been used by Brown and Escombe (3) in their important work on the 
energetics of green leaves, and by many others. 
Recently, Gurjar (7) has adopted Truog’s absorption tower, first used 
in soil analyses, for use in respiration studies. This tower consists 
simply of a vertical glass tube, ground into the neck of the flask which 
carries the caustic solution and filled to any desired height with glass 
1 Accepted for publication July 2, 1921. 
2 Reference is made by number (italic) to “ Literature cited,” p. 113-115. 
Journal of Agricultural Research, 
Washington, D. C. 
abf 
Vol. XXIII, No. 2 
Jan. 13, 1923 
Key No. G-264 
20517—23 - 4 
(101) 
