On the So-called Longitudinal Split of 

 Chronnosomes in the Telophase. 



(Preliminary Note) 

 By 

 Yoshiiwri Kiiwada. 



With Plate II. 



The idea is now growing that " crossing-over " occurs at an 

 earlier stage than that assumed on the basis of Janssens's original 

 chiasmatype theory (Plough/> 1917, Wilson,-> 1920), perhaps during 

 the synaptic phase or slightl3'- later. Since this idea is not in har- 

 mony with the hypothesis of tclosynapsis, even in the sense of Far- 

 mer, it is most desirable from the standpoint of the chromosome- 

 theory of heredity, to make a study of the so-called longitudinal 

 split of the chromosomes in the telophase, which, if it i» a true split, 

 seems to oppose the hypothesis of parasynapsis (Farmer,^-* 1912, 

 DiGBY,''^ 1919). The present work has been undertaken at the sug- 

 gestion of Professor E. B. Wilson during the writer's stay in Colum- 

 bia University. The work has been, to his great regret, temporarily 

 interrupted and in the following few pages the results, though very 

 incomplete, are briefl}' mentioned so far as obtained. 



There are two different opinions on the questions at what stage 

 of the nuclear life-cycle the longitudinal splitting of chromosomes for 

 the next division takes place ; one opinion is that it takes place in 

 the telophase of the preceding nuclear divison, and the other that it 

 comes to sight for the first time in the early prophase of the nucleus 

 which is preparing for its own division. An aspect in anaphasic, or 

 more generally in telophasic chromosomes which at first sight looks 

 very much like a split or sign of split, has been seen in a number of 



1) Jour. Exp. Zoology. Vol. 24. 1917. 



2) Am. Nat. Vol. 54. 1920 



3) Ann. Bot. Vol. 26. 1912 



4) Ann. Bot. Vol. 33. 1919. 



