WatTTERSON: EFFECT OF CHEMICAL IRRITATION 293 
that the carbohydrate which during normal growth is decomposed, 
in the processes of metabolism, to form oxalic acid, is not so 
transformed during the accelerated growth resulting from stimula- 
tion, but is immediately changed into constructive material for the 
plant body. Of this, the decrease in the economic coefficient 
(2. e., ratio of dry weight to sugar used) of the stimulated cultures 
seems an indication. Ovxalic acid is not, however, the only waste 
product of metabolism. Since, according to Pfeffer,* ‘a decreased 
formation of oxalic or other organic acids is accompanied by an 
increase in the ratio of CO, exhaled to the oxygen absorbed,” 
the amount of CO, given off under the varying conditions must 
also be reckoned with; it must be determined, that is, whether 
all the additional carbohydrate normally used to produce oxalic 
acid is now transformed into formative substance, or whether 
part of it may be wholly oxidized to produce larger quantities of 
CO,. This ratio of the dry substance produced to the amount of 
co, exhaled, or the respiratory quotient, was found by Kunst- 
mann} to vary with changing conditions, decreasing with a rise 
of temperature or with higher concentrations of the nutrient solu- 
tion. The effect of chemical stimulation was not included among 
the conditions. 
The effect of such stimulation upon respiration alone without 
regard to the possible acceleration of growth ensuing was studied 
by Jacobi,+ who obtained an increase in amount of CO, pro- 
duced by certain phanerogams, due to the influence of KCl, ‘NaCl, 
KNO,, iodine, chinin, antipyrin, oxalic acid and various organic 
Substances, Copeland ¢ obtained similar results; and likewise 
Kosinski $ in the case of fungi. * Morkowin Il found a decided 
* Pfeffer, W. Physiology of plants, ed. 2, 1: 527. 
Kunstmann, H. Ueber das Verhiltnis red oe und verbrauchter 
Nahrung. Leipzig. 1895. [Inaug. Diss. ] 
i Jacobi, B. Ueber den Einfluss verschiedener Substanzen auf die Athmung und 
| Kosinski, I. Die Athmun ng bei Hndpetseminden und unter Einwirkung vo 
mechanischen und chemischen Reizmittteln bei Asfergil/us niger. Jahrb. Wiss. Bot. 
‘| Morkowin, N. Recherches sur |’influence des anesthésiques sur la respiration 
des plantes. Revue Gén. de Bot. 11 : 289-303, 341-352. 1899. — Ueber den Ein- 
fluss ve ES ates auf die Kc ES Athmung der Pflanzen. Ber. Deut. 
21:72. 3 
Bot. G 
