292 WATTERSON: EFFECT OF CHEMICAL IRRITATION 
rapid growth and division, or to greater activity of the individual 
cells, has not been determined. 
Experiments were likewise performed by Ono on algae with 
like results except that the optimum concentration of the stimu- 
lants was much smaller. Similar work has been done on the 
phanerogams by Copeland and Kahlenberg * using pure metals as 
stimulants, by Townsend + with ether and HCl, and by Kahlen- 
berg and True.t Chapin § also found an increase in the growth 
of certain seedlings due to the presence in the atmosphere of 
small amounts of CO,, larger quantities of which acted asa poison. 
In all of these cases the amount of stimulation is indicated by 
the increase in the plant body, as shown by dry weight in the case 
of the fungi and algae, and by the increased surface of the organs 
of phanerogams. It is well known, however, || that only a part of 
the nutrient material absorbed by the plant is used to build up its 
living substance ; a part is continually being oxidized to provide 
the necessary energy for carrying on life-processes. Fully to de- 
termine, therefore, the relation between the plant and its food- 
supply, one would have to take into account both the amount of 
the latter which is used as constructive material, measured by the 
increased weight or size of the plant, and that which undergoes 
katabolic changes during which CO, and other waste products 
are liberated. 
Richards’ experiments were concerned with the first factor, 
that is, the amount of dry substance produced and its relation to 
the amount of sugar used, or the economic coefficient. . Ono con- 
firmed his results, and in addition he determined the relative quan- 
tities of oxalic acid produced by fungi under normal conditions 
and under stimulation, finding a decrease in the latter case with all 
substances tried except NiSO,. To account for this Ono suggests 
Si ee 
* Copeland, E. B., and Kahlenberg, L. The influence of the presence of pure 
metals upon plants, inn Wisc. Acad. 12: 454-474. 1899. 
+ Townsend, C. O. e correlation of growth under the influence of injuries. 
Ann. Bot. rr : 509-532. 1897. — The ray of hydrocyanic acid gas upon grains s and 
other seeds. Bot. Gaz. 31: 241-264, 
{ Kahlenberg, L., and True, R. os the toxic action of dissolved salts and 
their electrolytic dissociation. Bot. Gaz. 22 : 81-124. 96. 
2 sc . Einfluss der Kohlensiure auf das Wachsthum. Flora, gt : 348- 
379. 2. 
| Sac W. Physiology of plants, ed. 2, 1 : 287, 523. 1900. 
