2 Charles Russell Bardeen 



by its rays.^ Koernicke* found the development of yeast and 

 bacteria inhibited by exposure to the rays but that the exposed 

 cultures, if transferred to fresh unexposed gelatine, could begin to 

 grow again. 



The action of the Roentgen rays and radium on the higher 

 plants has been recently studied by M. Koernicke,^ who gives ref- 

 erences to the previous literature on the subject. Koernicke finds 

 that the Roentgen rays serve to check the growth of germinating 

 seeds. Immediately after exposure there may be a slight quicken- 

 ing' of growth. The retardation of development appears only 

 after a latent period. If the exposure to the rays is not too intense 

 or prolonged, the retardation of growth is merely transitory; if 

 sufficiently intense, there is permanent inhibition of growth. Ex- 

 posure of dry seeds and swollen, non-germinating seeds to the 

 Roentgen rays had no immediate inhibitive effect on subsequent 

 germination. Instead a slight quickening of germination was 

 sometimes seen. Ultimately, however, the roots of the exposed 

 seeds ceased to grow. According to Maldiney and Thauvenin^ 

 exposure to the Roentgen rays hastens germination of seeds. 

 Lopriore^ found the germination of pollen inhibited by the rays. 



A pupil of H. BecquereP found that while 24 hours' exposure of 

 certain seeds to radium rays caused no marked diminution in 

 power of germination, an exposure of a week or more inhibited 

 the process. Koernicke did not inhibit growth in the seeds he 

 studied (Vicia faba, Brassica napus, Papaver somniferum), but 

 he found that exposure to radium rays caused a subsequent check- 

 ing or inhibition of growth in germinating seeds and that non- 

 germinating seeds either dry or moist, if sufficiently exposed, 



^Aschkinass and Caspari: Arch, fiir die Ges. Physiol., Ixxxvi, 1901 (action attributed to a and 

 p rays). W. Hoffmann: Hyg. Rundsch, xiii, s. 913, 1903 (bacteria killed). Dixon and Wigham: 

 Nature, Ixix, pp. 81, 1903 (bacteria checked in growth). Danysz: Compt. Rend., cxxxvi, p, 463, 

 1903. H. v: Baeyer; Zeitschrift f . allgem. Physiologie, iv, p. 79, 1904. 



■^M. Koernicke: Berichte der Deutsche Bot. Gesellschaft, xxii, s. 163, 1904. 



'M. Koernicke: Ueber die Wirkung von RcJntgen- und Radiumstrahlen auf den pflanzlichen 

 Organismus. Berichte der Deutschen botanische Gesellschaft, xxii, pp. 148-166, 1904; xxiii, pp. 404- 

 414, 1905. 



*Maldincy and Thouvenin: Revue gen. de Bot., x, p. Si, 1898. 



'Lopriore: Estr. dal' Nuova Rassegna, Catania, 1897. 



*H. Becquerel: Comptes Rendus, t. 133, pp. 712, 1901. 



