OXYGEN RESPIRATION 21 



important role. Protoplasmic poisoning by unbalanced solu- 

 tions is at once revealed by a reduction in the rate of respiration. 

 Balanced solutions, on the contrary, produce no injurious effect 

 and the rate of respiration remains normal.^ 



The Influence of Chemical and Mechanical Stimulating 

 Effects on Respiration. — It is known that the reaction of living 

 protoplasm to various stimulating effects is subject to definite 

 laws.™ Weak stimulations effect an increased protoplasmic 

 activity which often exceeds that of untreated protoplasm. A 

 somewhat stronger stimulation evokes the same effect. After 

 a certain time, however, there follows a condition of proto- 

 plasmic fatigue and the activity then follows that of the normal 

 state. Very strong stimulations result at once in an appre- 

 ciable decrease in activity." 



The results of stimulation of the living cell may be due to the 

 alterations of the respiratory process. For example, wounding 

 evokes an increased protoplasmic activity for the purpose of 

 healing the wound." In this case there is a considerable 

 increase in the rate of respiration- and in the heat liberated. 

 Since in this case vigorous growth and formative process take 



. COo . , , 



place, the value of ^=r~ is lowered. 



1 Gustafson, F. G. J. Gen. Physiol. 2: 17. 1919-20; Brooks, M. M. Ibid. 3: 337. 

 1920-21. 



2B6hni. Bot. Zeitg. 45: 671. 1887; Stich, C. Flora. 74: i. 1891; Smirnoff. Rev. 

 gen. de bot. 15: 26. 1903; Tscherniaeff. Ber. d. bot. Ges. 23: 207. 1905; Richards. 

 Ann. of Bot. lo: 531. 1896; ii : 29. 1897; Zaleski, W. Ber. d. bot. Ges. 19: 331. 1901; 

 Dorofeieff. Ibid. 20: 396. 1902; Krasnoselsky, T. Ibid. 24: 134. 1906; and others. 



"» Another law than that referred to here appeared in the work of Lyon (The 

 role of phosphate in plant respiration. Thesis. Harvard. 1926; J. Gen. Physiol. 

 10: 599-615. 1926-27) when solutions of orthophosphate were applied to 

 Elodea canadensis. The resulting increase in production of CO2 was found to be 

 related to the concentration of PO4'" ion according to the equation 



(C02-62.475)(pP04-2.i3) = II4-43- 

 CO2 was stated in per cent and pP04 indicated the concentration of PO4'" ion 

 in the same way that pH is used to denote the concentration of hydrogen ions. — 

 Ed. 



" These rules for chemical stimulation are illustrated by the action of ether or 

 chloroform on respiration as measured by the production of CO2. Representa- 

 tive studies of this type are those of Brooks, M. M. J. Gen. Physiol, i : 193- 

 201. 1918-19; Thomas, H. S. Ibid. 1:203-207. 1918-19; Ray, G. B. 

 /6/</. 5: 469-477. 1922-23; Gustafson, F. G, Ibid.i: iS\-ig\. 1918-19. — Ed. 



° Both the conclusion and this teleological form of statement are open to 

 question. See also note 2 on page 13. — Ed. 



