— 387 — 



the division of this is very regular. The conjugation between the 

 components is end to end and is complete. 13 gemini. 



The intermediate types from the mixed populations are not 

 so regular in their divisions, as shown in figs. 7 a — g and 8 a — e. 

 It is the reduction of a plant from sowing V. 246, table III, p. 382 

 i. e. : a plant segregated from the very mixed population F in table 

 III). Its formula was: parv, n.lab, lut, n.mac, pinn, foliac (arven- 

 sis' size of petals, but the colour of tricolor). It was the plant sown 

 as V. 415 (p. 383). By its irregular divisions it discloses its 

 hybrid origin. 



In the early heterotypic anaphases seen from the pole most 

 frequently 14 bivalent and 1 or 2 single chromosomes can be 

 seen, as the following schedule over the pictured nuclei shows: 





bivalent 



univalent 

 (marked x) 



upper plate 



lower plate 





Fig. 7. d 



14 



1 (large) 



15 chromos. 



14 chromos. 





e 



13 



1 large 



2 little 



15 — 



14 — 





- f 



14 



1 large 

 1 little 



16 — 



14 - 





— g 



14 



(the two marked X X 

 only faintly joined) 



1 (little) 



14 



15 — 





— h 



13 



2 



14 — 



14 — 



Artificial 

 hybrid 



The chromosomes distribute irregularly to the poles, so that 

 the anaphase-plates contain different numbers of chromosomes. 

 One chromosome more or less seems not to afflict the viability 

 of the plants. Just as irregular are the artificial hybrids. In the 

 same anther nuclei with 13, 14, 15, 16, 17 and even with 11 and 

 12 chromosomes can be seen. Fig 7 h is of a beginning hetero- 

 typic anaphasis from Fx of a cross tricolor x arvensis (13 chromos. 

 X 17 chromos.). In the upper plate are 14 chromosomes and in 

 the lower one are also 14, but one from each (marked x) is single 

 and not conjugated, just as in the spontaneous hybrid. 



Fig. 8 shows the homotypic anaphases of the same spontaneous 

 hybrid. The following schedule shows the irregularities in this 

 division : 



25* 



