— 219 — 



Y. Miyaji (1913): Untersuchungen über die Chromosomenzahlen bei einigen 

 Viola- Arten. (Japanese. The results related in Ishikawa 1916). — Bot. 

 Magaz. Tokyo. Bd. 27. 



C. Raunkiær (1918): Ueber den Begriff der Elementarart im Lichte der 

 modernen Erblichkeitsforschung. — Zeitschr. f. indukt. Abst.- und 

 Vererbungslehre. Bd. 19. 



O. Rosenberg (1909): Gytologische und morphologische Studien an Drosera 

 longifolia & rotundifolia. — Kungl. svenska Vetenskaps-Akad. Hand- 

 lingar. Bd. 43, No. 11. 

 — (1918): Chromosomenzahlen und Chromosomendimensionen in der Gat- 

 tung Crepis. Arkiv för Bot. Bd. 15. 



G.Tischler (1915): Chromosomenzahl, -Form und -Individualität im Pflanzen- 

 reiche. — Progress. Rei Botanicæ. Bd. 5. 



V. B. Wittrock (1897): Viola-Studier I. Morfologisk-biologiska och sy- 

 stematiska studier öfver Viola tricolor (L.) och hennes närmare anför- 

 vandter. — Acta Horti Bergiani. Bd. 2, No. 1. 



Explanation of plates. 



All the figures except the fig. 25 are from pollen mother cells. The figures 

 are drawn with Abbe's camera under an 1,4 mm Phluorite homog. immer- 

 sion Winkel with comp. oc. Zeiss 12. The enlargement here is about 2500 

 times. The scale indicates fi. 



Plate I. 



Fig. 1 : Viola tricolor. Synapsis-like stage. 



Fig. 2 — 3: Viola arvensis. Synapsis-like stage. The coil somewhat more con- 

 tracted and the threads thicker, than in fig. 1. Parallel, not paired 

 threads of an appearance like a string of beads. 



Fig. 4 — 7: Viol. arv. Beginning diakinesis. The threads appear segmentated, 

 and the gemini are about to be differentiated in the ends of the 

 segments. 



Fig. 8 — 10: Viol. arv. Three different nuclei in early diakinesis (8 a and 8 b 

 of the same nucleus and so on). The dyads in the shape of "bent 

 dumb bells" are the double-chromosomes (gemini). 



Plate II. 



Fig. 11 — 12: Viol. arv. Heterotypical metaphasis. In the nucleus 11 probably 

 more than 30 chromosomes. Fig. 12 does not represent a complete 

 nucleus. 



Fig. 13 a and b: Viol. arv. Heterotypical anaphasis. Four small chromosomes 

 are seen in the linin strands between the pole plates; 2 chromosomes 

 from the bottom and 1 from the top pole plate have been carried 

 by the knife to the left side. 2 X 15 chromosomes of a different 

 size. The arrow indicates the direction of the cut. 



Fig. 14: Viol. arv. Homoetypical anaphasis seen from the side. Very regular. 



Figs. 15 — 16: Viol. arv. Homoetypical anaphasis seen from the pole. The two 

 plates belong to same tetrad. Fig. 15 is seen in the upper part of 



