ATYPICAL MITOSIS AND OTHER NUCLEAR PHENOMENA 187 



vacuolation.'i The chromatic matter of the nucleus may contract into a 

 deeply staining mass (pyknosis), diffuse in the karyolymph (karyolysis), 

 or adhere to the membrane. Nuclei about to divide are prevented from 

 doing so, but those in division usually continue or complete the process. 

 Mitosis is often very aberrant, ^^ in many respects resembling that seen 

 in chloralized cells (Fig. 109). The chromosomes are irregularly dis- 



D 



Fig. 109. — The effect of Rontgen rays on mitosis in cornea cells of Salamandra. A, 

 chromatic bridge. B, " pseudoamitosis." C, distribution of chromosomes to three cen- 

 ters. D, partial pyknosis; some of the chromosomes have passed to the poles. {After 

 Alberti and Politzer, 1923.) 



tributed, hence nuclei and cells with polyploid or otherwise altered 

 chromosome complements are frequently observed in irradiated tissues. 

 The reported occurrence of just such phenomena in ordinary and arti- 

 ficially induced tumors^^ has excited much interest in connection with the 

 cancer problem, i"* but at present very little can be said concerning causal 

 relationships. 



Of great interest are the more definitely localized effects produced 

 by irradiation with X-rays. ^^ It is found that with proper dosages a 



11 Nadson (1925), Bisceglie and Bucciardi (1929). 



12 E.g., Komuro (1917 et seq.), Pekarek (1927), and Patten and Wigoder (1930) on 

 Vicia roots; Alberti and Politzer (1923, 1924) and Politzer (1925) on cornea cells; 

 Strangeways and Oakley (1923), Strangeways and Hopwood (1926), and Kemp and 

 Juul (1930) on tissue cultures; Pauli and Hartmann (1924) and Pauli and Politzer 

 (1929) on cathode rays; and Bersa (1927) on Zea roots. 



13 In animals: Howard and Schultz (1910), Boveri (1914a), Bichler (1914), Yama- 

 giwa and Ichikawa (1915 et seq.), Lewis and Lockwood (1929), Winge (1930a), Levine 

 (1931, good bibliography), and others. 



In plants: Komuro (1922, 1924f/e, 1925a6c, 1928a6c, 1930ac), Winge (1927^), 

 Levine (1929), Goldschmidt and Fisher (1929). 



" See the reviews by Ludford (1925) and Levine (1931). 



15 H. J. MuUer (1926, 1927, 1928a6c, 19296c, 1930a6c), Muller and Painter (1929), 

 Painter and Muller (1929), Muller and Altenburg (1930), J. T. Patterson (1928, 1929, 

 1930a6, 1931a), Patterson and Painter (1931), Mavor (1921, 1922, 1923o6c, 1925), 

 Hanson (1928), Dobzhansky (1929a6cd, IdSOad, 1931a6). The foregoing are on 

 Drosophila. For general accounts, see Muller (1929c, 19306). In plants: Stadler 

 (1928a6c, 1929, 1930a5c, 1931a6, 1932), Goodspeed and Olson (1928a6), Goodspeed 

 (1929o6, 1930a6c, 1932), Goodspeed and Avery (1930), de Mol (19306, 1931a6c), 

 M. Nawaschin (1931c), Delaunay (1930), Randolph (1932), Lewitsky and Araratian 

 (1931). For a general statement, see Stadler (19306). 



