Studies on the Cytology of some Species of Taraxacum. 
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form of X, Y, V, or 0, as in Figs. 10 — 11, which is characteristic of 
the heterotypic division with long chromosomes. 
The contraction and condensation of the chromosomes, which occur 
in the spirem stage, continue tili later stages, so each double chromo- 
some thickens and shortens more and more (Fig. 12), and finally changes 
into dumb-bell- or hour-glass-shaped body (Figs. 13 — 14). These chromo- 
somes are now distributed looseiy near the periphery of the nuclear 
cavity. 
The number of chromosomes is easily to be counted in the 
diakinesis stage, and many careful observations revealed it to be 
eight for the gametophyte. As Rosenberg (1909) States that the 
reduced number of chromosomes in T. confertum is eight, the latter 
agrees in the number of chromosomes with T. platycarpum, at least 
in their haploid number. 
Up to this stage the large nucleolus is yet to be seen in the nucleus 
(Fig. 14), but shortly afterwards the nuclear membrane as well as the 
nucleolus disappear, and the multipolar spindle appears in cytoplasm 
(Fig. 15), which is soon followed by a normal bipolar spindle. The eight 
double chromosomes, which are distributed irregularly in the cytoplasm, 
now arrange themselves on the equatorial plate as in Fig. 16, and at this 
stage the number of chromosomes can be counted very easily in the polar 
view (Fig. 17). 
Every bivalent chromosome then splits in two univalent ones, 
and the daughter-chromosome moves towards both ends of the spindle. 
Fig. 18 shows the anaphase of the heterotypic division, seen moreorless 
obliquely, and we may easily convince ourselves that each group of chro- 
mosomes consist of eight of them. 
The diploid number of chromosomes in this species has been observed 
in the wall-cell of young ovules, and it proved to be sixteen. So the first 
nuclear division of pollen-mother-cells must be a heterotypic and re- 
ducing one. In the telophase of the first division the longitudinal fission 
of the chromosomes, preparing for the next division, is often observable, 
when the chromosomes become angular or amoeboid and pass into the 
more or less anastomosing condition, being followed by the formation of 
the nuclear membrane and the nucleoli, as shown in Fig. 19. This con- 
dition, however, seems to continue rather for a short time and the spindles 
of the second mitosis appear quickly. Fig. 20 shows the prophase of 
this mitosis, in which the two spindles are placed perpendicularly to 
each other, and the split chromosomes arrange themselves very regularly 
on the equatorial plate. At this stage we may also easily calculate 
