Jan. 13,1923 
New Respirometer for Seeds 
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2. Volume of the respiring material (to 0.1 cc.). 
3. Net volume of air in the apparatus (1 — 2). 
4. Weight of the respiring material (to 1 mgm.). 
5. Percentage dry weight of the respiring material (this to be deter¬ 
mined in material duplicating that which is used in the respiration 
experiment). 
6. Dry weight of the respiring material from (5) (to 1 mgm.). 
All necessary data must be carefully recorded at the beginning and 
end of each period of a respiration experiment. It is convenient to 
keep the data for each period in compact form on a 3 by 5 inch card 
or on a separate sheet of a 3 by 5 inch loose-leaf note book. The fol¬ 
lowing form is suggested : 
Exp. begun. 
No. of period (1, 2, 3, etc.) 
Stoppers inserted. 
Stopcocks closed. 
Barometer. 
Manometers read. 
Caustic used. 
Barometer . 
Manometer readings: 1 ... 
Before adding caustic 
After adding caustic. 
Remarks: . 
; Material. 
.; Temp 
at. 
. °C.; = .. 
at. 
....... /°C. = .. 
.: 2 . 
' A . . 
.. at o°C. 
The absolute net volume of an apparatus uncorrected for pressure or 
temperature is a base from which all other volumes are calculated, is 
uniform through any one set of calculations, and therefore need not be 
determined closer than to tenths of a cubic centimeter. On the contrary, 
the changes in volume of the gas it contains, corrected to standard con¬ 
ditions, are the actual data for respiratory exchanges. Inaccuracies ap¬ 
proaching o. 1 cc. in determining these volume changes would sometimes 
seriously affect the results of an experiment. All volume computations 
should therefore be carried to hundredths of a cubic centimeter. For 
the same reason corrections of apparent volume for the changed posi¬ 
tions of the mercury in the manometers should always be made. These 
corrections will frequently amount to more than 0.1 cc. The caustic 
solution used should be measured with all possible accuracy and should 
not be stronger than 20 per cent on account of the impossibility of ac¬ 
curate measurement of a stronger, more viscous solution. As indicated 
on a previous page, corrections may also be introduced for the short 
periods of time between the different operations. 
Table I illustrates the calculation of gas volumes and units of respiratory 
exchanges (milligrams oxygen and C 0 2 per gram dry weight of the 
respiring material in 24 hours) from data recorded at the beginning of 
an experiment and at the beginning and end of one experimental period. 
The data are taken from the first period of a respiration experiment with 
duplicate lots of 50 Newtown Pippin apple seeds in a very early stage of 
germination. The symbols in the left-hand margin of the table are used 
for convenient reference in later parts of the table to the quantities to 
which these symbols refer. The formulae, with their numbers, are 
taken from the preceding section. In practice the form in which these 
calculations are given can be considerably shortened. 
