1922] SEARS—TARAXACUM 317 
divergent form of it. The chromosome forms in the two sets of 
figures show no interrelation, but a common origin at segmentation. 
It will particularly be noted that connections between chromo- 
somes persist in the beginnings of the elongated stage but not in 
_diakinesis, making it quite unlikely that the former is a derivative 
of the latter, but not militating against the idea that both are 
derivable from late segmentation. 
The nucleus in the elongated stage is often lobed, moreover, 
as in fig. 40, and constricted and binucleolate as in fig. 41. In 
short, the elongated nucleus with about twenty-six X and Y- 
shaped chromosomes must be regarded as part of a distinct sequence 
TABLE I 
Stage Sequence A Sequence B Sequence C Sequence D 
ee scar apres’ ...| 13 pairs | 13 pairs 13 pairs 13 pairs 
yee Oc ormal Normal Normal Normal 
Loose skein oe ee. Normal Normal Normal Norma: 
Splitting 6 Visible Visible Visible Visible 
ieee APE ae 26 cuboids 26 cuboids 26 cuboids 26 X’s and 
s; nucleus 
Synapsis.........| Prompt Slow Slow or none; | None 
: nucleus long 
Orientation....... Compact Loose rregular None; nucleus 
lobing 
opmdle: 5... 5k. Fibers to Fibers to Defective None 
bivalents univalents 4 
Metaphase....... Qualitative, Quantitative, | None or very | Amitosis 
pes arrow broad irre: r 
Second division ...} Quantitative, | Quantitative, | None, irregu- None or 
homotypic somatic (or lar or amitotic | amitotic 
n 
arising from segmentation and culminating in amitosis, and not as 
a curious step in the normal maturation process. This amitotic 
type of development may be designated as sequence D (table I). 
It is illustrated in figs. 36-42. 
Returning to diakinesis with its twenty-six cuboid chromosomes, 
this stage may develop further in any one of the three ways outlined 
in table I, and designated as sequences A, B, and C respectively. 
Type A is illustrated in figs. 16-22. Here pairing is end to end, 
following diakinesis, and is both prompt and complete. Orienta- 
tion is uniform and compact, resulting in a heterotypic metaphase 
