346 CHARLES PACKARD 



distinguished. And should the behavior of the chromosomes in 

 Ascaris find a counterpart in the behavior of the chromosomes 

 of the bugs we would have a simple and elegant method of testing 

 some of the hypotheses concerning the role of the X chromosome. 



SUMMARY 



1. Very mild radiation by means of the gamma rays from 50 

 mg. of radium bromide produces an acceleration in the rate of 

 cell division in Arbacia without producing any abnormalities. 

 These rays have no effect on the development of Nereis or 

 Drosophila. 



2. Moderate stimulation by means of the beta rays, obtained 

 by separating them from the gamma rays in a strong magnetic 

 field, brings about a retardation of growth in Arbacia and 

 Nereis, which is followed by no abnormalities. 



3. More intense radiation in which both beta and gamma rays 

 are used, results in a liquifying of the protoplasm in the Nereis 

 egg, and the development is abnormal. The eggs of Arbacia 

 show no protoplasmic changes, but the chromatin is injured. 



4. There is no evidence for parthenogenetic development. 



5. Acceleration and retardation may be caused by a change 

 in the rate of enzyme action brought about by the radium 

 treatment. 



LITERATURE CITED. 



Abbe, R. 1912 An improved method of using radium. Med. Rec, Feb. 10. 



1914 Radium Beta Rays. Med. Rec, Nov. 28. 

 CoNGDON, E. D. 1912 A comparison of the alteration in the velocity of growth 



of certain seedlings through the action of the rapid and slow electrons 



of the beta rays of radium. Arch. f. Entwickl., Bd. 24. 

 Gager, G. S. 1908 EfTects of the rays of radium on plants. Mem. N. Y. Bot. 



Gardens, vol. 4. 

 GuiLLEMiNOT, H. 1907 Effets compares des rayons X et des radium sur las 



cellule vegetal. Compt. Rend. Acad. Sci. Paris, T. 145. 

 Hertwig, G. 1911 Das Schicksal des mit Radium bestrahlten Spermachro- 



matins im Seeigelei. Arch. f. mikros. Anat., Bd. 77. 

 Hertwig, P. 1911 Durch Radiumbestrahlung hevorgerufene Veranderungen 



in den Kernteilungsfiguren der Eier von Ascaris megalocephala. 



Arch. f. mikros. Anat., Bd. 77. 



