I 4 4 MOVEMENTS OF CURVATURE 



affected by the transference of the plant to pure oxygen at atmospheric 

 pressure l . The injurious action of oxygen observed by Kabsch, in a few 

 cases, is apparently due to the presence of poisonous impurities, oxygen 

 made from potassium chlorate usually containing traces of chlorine unless 

 carefully purified. Kabsch also found that the irritability was retained in 

 nitrous oxide, but Correns 2 has shown that this is not the case with the 

 stamens of Berberis, while Borzi 3 found that Mimosa soon becomes rigid 

 in this gas. Borzi states that Mimosa regains its irritability and power of 

 movement after being for some time in an atmosphere of nitrous oxide, but 

 this is probably due to the presence of free oxygen in the nitrous oxide, 

 coupled with the gradual accommodation of the plant to a low partial 

 pressure of oxygen. Pure carbon dioxide is highly injurious and produces 

 a rapid suspension of irritability 4 . 



Ether and Chloroform. All poisonous substances affect the power of 

 movement when sufficiently concentrated, but the action of anaesthetics 

 is of especial interest, since by them the reactions may be analysed and 

 their character revealed to a greater or less extent 5 . 



It has long been known that ether and chloroform suspend the irritability 

 of the pulvini of Mimosa pudica and of the stamens of Berberis. The 

 same applies to the leaves of Dionaea*, the stigmas of Bignonia and 

 Catalpa" 1 , and the stamens of Cynareae. Moderate doses of chloroform 

 suspend the seismonic irritability of Mimosa^ but not the daily and auto- 

 nomic movements of the leaves. It is not certain whether these latter 

 movements can in all plants be temporarily suspended by anaesthetization 

 without causing permanent injury. In fact a complete suspension of the 

 irritability of tendrils, of thermonastic and photonastic movement, and 

 of growth 8 in general seems only to be produced by anaesthetization which 

 seriously injures the plant when slightly more prolonged. Slight etheriza- 

 tion produces a temporary acceleration of growth, but it is not certain 

 whether such treatment also accelerates induced curvatures. 



Darwin 9 observed no suppression of irritability in etherized tendrils, 



1 Correns, Flora, 1892, pp. 109, 120, 150. 



2 Correns, I.e., pp. 108, 150. 



3 Borzi, Rivista di Scienze Biologiche, 1899, Fasc. IV; Bot. Centralbl., 1899, Bd. LXXX, p. 351. 



4 Correns, I.e., pp. 109, 121, 130. 



5 On the influence of different substances see Goppert, De acidi hydrocyanici vi in plantas com- 

 mentatio, 1827 ; Marcet, Biblioth. universelle de Geneve, Archiv, 1848, Bd. LX, p. 204; Bert, Me"m. 

 de 1'Acad. de Bordeaux, 1866, p. 30; Bernard, Le9ons s. 1. phenomenes de la vie, 1885, 2 e e"d., T. l, 

 p. 258 ; Tassi, Nuovo giornale botanico italiano, 1887, T. IX, p. 30; Krutickij, Bot. Centralbl., 1889, 

 Bd. xxxix, p. 379; Borzi, L'apparato di moto delle Sensitive, 1899; Paoletti, Nuovo giornale 

 botanico italiano, 1892, T. xxiv, p. 65. 



6 Darwin, Insectivorous Plants. 



7 Heckel, Compt. rend., 1874, T. LXXIX, p. 702. 



8 Detmer, Landw. Jahrb., 1882, Bd. XI, p. 227; Townsend, Annals of Botany, 1897, Vol. XI, 

 p. 522. 



9 Darwin, Climbing Plants. 



