2l6 



PHYSIOLOGY OF NUTRITION 



Zaliesskii 1 found that if the bulbs of Gladiolus are immersed in water for a 

 short time their respiratory activity is considerably increased. 



Changes in concentration of the nutrient solution affect the value of the 

 respiratory ratio. Purievich 2 obtained the following values of this ratio for 

 Aspergillus niger with different concentrations of cane-sugar solution. 



Concentration of the medium, per cent 1 5 10 20 25 



Respiratory ratio, 



/ C0 2 



v o 2 



0.85 0.96 1.04 0.93 0.73 



Respiration is influenced by various toxic substances. 3 Morkovin 4 studied 

 this effect in the case of various alkaloids, glucosides, alcohols and other sub- 

 stances, such as ethyl ether, formaldehyde and paraldehyde, and found that 

 these increase respiratory activity when present in very weak concentration. 

 For example, of two similar groups of shoots of etiolated bean seedlings one 

 group was grown in cane-sugar solution, and the other in the same solution with 

 the addition of 1 per cent, of isobutyl alcohol. Without the poison, 100 g. 

 of shoots produced 65.0 mg. of carbon dioxide per hour during the first twenty- 

 four hours of the experiment, and 72.4 mg. per hour during the first thirty-seven 

 hours. With the poison, 191. 7 mg. of carbon dioxide was produced per hour for 

 the first twenty-four hours and 124.5 mg. per hour for the first thirty-seven 

 hours. Isobutyl alcohol, in this concentration, is thus seen to exert a definitely 

 accelerating effect upon respiration. Zaliesskii 5 has shown that ether accelerates 

 respiration in resting plant organs to a marked degree ; in the case of Gladiolus 

 bulbs exposed to an atmosphere containing ether, respiration is first increased, 

 but later decreases to below the normal rate. 



Wounding markedly increases the rate of respiration. 6 In one experiment 

 300 g. of uninjured potato tubers produced from 1.2 to 2 mg. of carbon dioxide 



1 Zaliesskii, V.. Influence de l'excitation sur la respiration des plantes. [Russian, French sub-title only. J 

 Mem. Inst. Agron. et Forest. Novo-Alexandria 15 2 : 1-41. 1902. [Parts of vol. are separately paged.] 



2 Puriewitsch, K., Physiologische Untersuchungen iiber Pflanzenatmung. Jahrb. wiss. Bot. 35: S73~ 

 610. 1900. 



3 Palladin, W., Ueber die Wirkung von Giften auf die Atmung lebender und abgetoteter Pflanzen, 

 sowie auf Atmungsenzyme. Jahrb. wiss. Bot. 47: 431-461- 1910. 



1 Morkowin, N., Recherches sur l'influence des anesthetiques sur la respiration des plantes. Rev. 

 g6n. bot. 11 : 289-303, 3J1-352. 1899. Idem, Recherches sur l'influence des alcaloides sur la respiration 

 des plantes. Ibid. 13: 109-126, 177-192, 212-226, 265-275- 1901. 



6 Zaliesskii, 1902. [See note 1, this page.] 



« Stich, Conrad, Die Athmung der Pflanzen bei verminderter Sauerstoffspannung und bei Verletzungen. 

 Flora 74: 1-57. 1891. P. IS. Pfeffer, W., Ueber die Steigerung der Athmung und d-r Warme-production 

 nach Verletzung lebensthatiger Pflanzen. Ber. u. d. Verh. d. K. Sachs. Ges. Wiss. Leipzig (Math.-phys. 

 CI.) 48: 384-389. 1896. Smirnoff, Influence des blessures sur la respiration normale et intramoleculaire 

 (fermentation) des bulbes. Rev. g6n. bot. 115: 26-38. 1903. 



