248 Franklin Kidd. 
LABORATORY EXPERIMENTS ON THE SPROUTING 
OP POTATOES IN VARIOUS GAS MIXTURES. 
(Nitrogen, Oxygen and Carbon Dioxide). 
By Franklin Kidd, D.Sc. 
Food Investigation Board, Department of Scientific and Industrial Research. 
A/iETHOD. Potatoes were enclosed in glass desiccators of 
*■ about 3,000 cc. capacity and the artificial gas mixtures were 
made up by the method previously described. 1 This method involves 
partial or complete evacuation of the vessel containing the tubers 
before passing in from cylinders of compressed gas the different 
gases in the proportions required. Five potatoes were the most that 
could be used in any experiment. With such a small number the 
probable error due to individual variation is large. To decrease this 
the following precautions were taken. In any comparative series the 
potatoes were carefully selected so that in all experiments they 
should be of the same weight, size and number, and of the same 
sprouting capacity as estimated by previous tests. 
The sprouting capacity was judged by (1) the number of sprouts, 
(2) their vigour ( i.e . size). Every time an observation was made all 
the sprouts which had appeared were broken off. The results are 
given in number of sprouts, total weight of sprouts, and weight per 
100 sprouts. From a series of controls the average error of a single 
reading from 5 potatoes was calculated to be under 15 per cent. 
Even with five potatoes it was found necessary to renew the gas- 
mixtures every two days. The variation in concentration of 0 2 and 
C0 2 during the experiments was not more than from 2 to 3 per cent. 
The experiments were conducted in a dark room the daily 
temperature variation of which was from 1-2 degrees. The season 
was from June to December, 1918. The average monthly temper¬ 
ature of the dark room was as follows:— 
June 
17°C. 
Oct. 
13°C 
July 
19°C. 
Nov. 
13°C. 
Aug. 
20°C. 
Dec. 
13-14°C. 
Sept. 
15°C. 
Material. 
The “Factor” 
potatoes used were 
taken on the 
24th April from the clamp where they had already sprouted some¬ 
what. From 24th April to 31st May they were kept in a dark, cool 
and dry place in the laboratory. Sprouts had again developed in 
this interval, and these were removed before using the potatoes for 
the following experiments. The “ King Edward’s,” which were not 
used until late in the season, had several times produced sprouts 
which had been removed. 
* Kidd, F., Proc. Roy. Soc. (Lond.), B. 87, 1914,'411. 
