EFFECT OF X-RAYS ON RATE OF CELL DIVISION. 95 



He also says, " It would appear as if the nuclei in mitosis were 

 forced into a resting stage in the spindle by the X-rays." 



Finally, O. and G. Hertwig have carried on a thoroughgoing 

 series of studies on the influence of radium upon developing eggs 

 and larvae of amphibians. This set of observations includes first, 

 the nature of the pathological changes due to radiation which are 

 found to occur in the various organ systems and in the body form, 

 and second, the effects of the radiation upon the nuclei and cyto- 

 plasm of the various tissues. The evidence is found to support 

 the view that the nuclei are injured directly. In the early 

 stages injury and general retardation of development take place; 

 the effect, however, on the rate of cell division is not discussed, 

 I believe, by either writer. 



LITERATURE. 

 Bardeen, C. R. 



'09 Variations in the Susceptibility of Amphibian Ova to X-Rays at Different 



Stages of Development. Anat. Record, Vol. III. 



'n Further Studies on the Variation in Susceptibility of Amphibian Ova to 

 X-Rays at Different Stages of Development. Amer. Jour. Anat., Vol. XI. 

 Barlow, Lazarus, W. S. and Bonney, Victor. 



'09 The Influence of Radioactivity on the Division of Animal Cells. Archives 

 of Middlesex Hospital, Vol. 15. (Accessible to me only through reviews.) 

 Becquerel, H. 



'01 Sur quelques effets chimiques produits par le rayonnement du radium. 



C. R. de 1'Acad. de Sci., T. 133, p. 709. 

 Bohn, G. 



'03 Influence des rayons du radium sur les oeufs vierges et fecondes, et sur les 

 premiers stades du devellopment. C. R. de 1'Acad. de Sci., T. 136, p. 1085. 

 Congdon, E. D. 



'12 The Influence of Radiations of Radium upon the Embryonic Growth of the 

 Pomace-fly, Drosophila ampelophila, and upon the Regeneration of the 

 Hydroid, Tubularia crocea. Bull. Mus. Comp. Zool., Vol. 53, No. 7. 

 'i2a. A Comparison of the Alterations in the Velocity of Growth of Certain 

 Seedlings through the Action of Rapid and Slow Electrons of the Beta Rays 

 of Radium. Arch. f. Entw-m., Bd. 34. 

 Conklin, E. G. 



'97 Embryology of Crepidula. Jour, of Morph., Vol. 13. 



'02 Karyokinesis and Cytokinesis. Jour. Phila. Acad. Nat. Sci., Vol. XII. 



'12 Experimental Studies on Nuclear and Cell Division in the Eggs of Crepidula. 



Jour. Phila. Acad. Nat. Sci., Vol. XV. 

 Gager, C. Stuart. 



'08 Effects of the Rays of Radium on Plants. Mem. N. Y. Bot. Garden, IV. 

 Gilman, P. K. and Baetjer, F. H. 



'04 Some Effects of Roentgen Rays on the Development of Embryos. Amer. 

 Jour. Physiol., X., p. 222. 



