NOTES 717 



294. Kabsch : Lc. [288], pp. 33 sqq. H. Miiller : Alpenblumen, Leipzig, L881. 

 G. Haberlandt : Lc. [274J, p. 34. K. Linsbauer : Sitzb. Wien, 114, L905. Brunn: 

 Unters. iib. Stossreizbarkeit (Inaug.-Diss.), Leipzig, 1908. Both Linsbauer and 

 Brunn regard the stamina! hairs of the Cynareae as stimulators, and not as actual 

 organs of perception. Cf. G. Haberlandt : I.e. [274 j, pp. 46-7. 



295. [For stamina! hairs of Centaurea Jacea cf. also Kny's Wandtafeln, PI. L05 

 and text, pp. 480-482.] 



296. G. Haberlandt : I.e. [274], pp. 101 sqq. 



297. Conn : Cohn's Beitr. 1, 1861. Goebel : Pflanzenbiologische Schilderungen, 

 2, 1891, p 72. G. Haberlandt : l.c. [274], pp. 129 sqq. 



298. Sydenham Edwards : Curtis's Bot. Mag. 20, 1804. Oudemans : Versl. en 

 Med. Akad. Amst. 9, 1859. Ch. Darwin : l.c. [285], pp. 259 sqq. Munk : Die 

 elektrischen u. Beugungserscheiiimigen am Blatte d. Dionaea museipula, Leipzig, 

 1876. Batalin : Flora, 1877.' Goebel : Lc. [297], pp. 69, 201. Macfarlane : Contrib. 

 Bot, Lab. Pemi. 1, 1892. G. Haberlandt : l.c. [274], pp. 133 sqq. 



299. Cheeseman : Trans. N.Z. Inst. 5, 1873. Fitzgerald : Australian Orchids, 

 1, Sydney, 1882. Haberlandt : I.e. [274], pp. 85 sqq. 



300. Knight : Phil. Trans. 1806. 



301. Noll : Ub. heterogene Induktion, Leipzig, 1892, pp. 42 sqq. Id. I.e. [280J. 

 Id. P.J. 34, 1900. Noll was the first to suggest that plants might perceive gravita- 

 tional stimuli hi the same way as animals do, namely, with the aid of statocyst- 

 like sense-organs ; but he believed that the organs in question were ultra-microscopic 

 structures located in the ectoplast. The author and Nemec, on the other hand, both 

 arrived independently at the conclusion, that the statocysts of plants consist of 

 entire cells, and that most gravitational sense-organs are made up of a number of 

 statocysts. Cf. Nemec : Ber. 18 (1900) and 20 (1902). Id. P.J. 36, 1901. G. Haber- 

 landt : Ber. 18 (1900) and 20 (1900). Id. P.J. 38 (1903) and 42 (1905). 



302. F. Darwin and Miss Bateson : A.B. 2, 1888-9. Fitting : P.J. 41 (1905). 



303. The fact that a root with the apical -5 to 1 mm. cut off does not curve 

 geotropically, when laid on its side, though it continues to grow in length, led Ch. 

 Darwin to conclude that geotropic sensitiveness is confined to the root-tip. Tins 

 view, which is supported by other facts as well, has been the subject of a considerable 

 amount of controversy. Wiesner found that decapitated roots, on being exposed 

 to centrifugal force of 20 g. to 41 g. intensity, curved " geotropically " after sonic 

 time in the region of most active growth ; he accordingly denies the localisation of 

 geotropic sensitiveness. Czapek, on the other hand, supports Darwin's theory ; 

 but the experiments with glass caps upon which his arguments are based, are not 

 universally accepted as conclusive. Recently, Piccard has attacked the problem 

 in a new way, by causing centrifugal forces to act in opposite directions upon the 

 apex and the growing zone of a root made to revolve around a horizontal axis. Tliis 

 result was attained, by affixing the root in such a manner that it formed an angle 

 with the axis of rotation, a point situated between apex and growing zone being 

 centred on the axis. Piccard concludes, that not only the root-tip, but also the 

 entire growing zone is capable of perceiving gravitational stimuli, and that the latter 

 is actually the more sensitive of the two. As both Piccard's experimental method 

 and his interpretation are open to criticism, the author has repeated his experiments 



