ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 607 



■of the epidermis may be in inverse proportion to the activity of the 

 central cylinder, lateral roots often appearing when hairs are suppressed, 

 and vice versa. 



Arrangement of Starch in the Starch-Sheath of the Perianth of 

 Clivia.* — L. Gins, investigating the arrangement of the starch in the 

 perianth-leaves of Clivia nobilis, finds only under the most favourable 

 circumstances a tendency of the starch grains to lie on the physically 

 lower cell-walls ; in the great majority of cases no such tendency was 

 shown. The perianth shows positive geotropism ; and Nemec had 

 previously described the presence of a starch-sheath with well marked 

 statolithic starch-grains. 



Irritability. 



Heliotropism Induced by Radium.f — Hans Molisch records a posi- 

 tive curvature in stems of seedlings when presented to rays from sealed 

 tubes containing a mixture of radium bromide and zinc sulphide ; he 

 also confirms Dixon's result as to the failure of radium bromide alone to 

 induce curvature. The author regards the curves as heliotropic, induced 

 indirectly by radium. He also notes the interesting fact that the 

 experiments usually fail in the greenhouse but succeed in the laboratory, 

 and suggests as an explanation, that the impurities in the air of the 

 laboratory tend to reduce negative geotropism and thereby increase the 

 -sensitiveness to phosphorescence and the heliotropic stimulus. 



Influence of Light on Sporogonium-formation in Liverworts.^ — 

 W. Kinzel indicates an interesting contrast between the action of light 

 on the sexual and asexual generation. He finds that light is favourable 

 to the formation of sporogonia, whereas it exercises an unfavourable 

 influence on leaf -development. 



Influence of Temperature on Respiration.§ — M. K. Pourievitch 



has re-investigated the relation between temperature and the ratio of the 



two gases concerned in the process of respiration. He points out sources 



of error in the work of Bonnier and Mangin on the result of which it 



has been generally concluded that variation in temperature has no effect 



CO 

 on the ratio -^p, and shows from his own experiments that the ratio 



changes with the temperature, becoming greater as temperature rises. 

 This effect is most noticeable in young organs, and depends on the 

 nutritive substance present in the tissues, the influence of temperature 

 becoming less as the nutritive substance disappears. 



Traumatic Curvature in Roots.|] — G. P. Burns has repeated 

 Spalding's experiment on traumatic curvature in roots. The previous 



* Oesterr. Bot. Zeitschr., lv. (1905) pp. 92-6 (7 figs, in text). 

 t Ber. Deutsch. Bot. Ges. xxxiii. (1905) pp. 2-7 (fig. in text). 

 X Naturwiss. Zeitschr. Land. Forstw.,iii.( 1905) pp. 120-4. See also Bot. Centralbl., 

 xcviii. (1905) p. 624. 



§ Ann. Sci. Nat. Bot., ser. 9, i. (1905) pp. 1-32. 



| Beiheft. Bot. Centralbl., xxviii. (1904) pp. 159-64 (4 figs, in text). 



2 S 2 



