320 BOTANICAL GAZETTE [APRIL 
Discussion 
The more important implications of these findings fall under (2) 
relation to previous hypotheses explaining maturation in partheno- 
genetic species of Taraxacum; (2) effect upon interpretations of 
normal reduction division (particularly as to synapsis) which have 
been based upon comparisons of sexual and parthenogenetic species 
of Taraxacum; (3) elucidation of the findings themselves in terms 
of the fundamental cell activities involved. 
1. JUEL’s (12) hypothesis, accepted in more or less modified 
form by subsequent workers, is that maturation, in Taraxacum 
officinale begins as a heterotypic and shifts to a homotypic division. 
As previously stated, this is based upon his belief that the elongated 
nucleus with X-shaped chromosomes follows diakinesis and precedes 
spindle formation. Since, as has been indicated, the elongated 
nucleus is a member of a distinct sequence, the hypothesis is placed 
upon the defensive. Barring this discrepancy, however, the type 
of division described by JUEt is essentially that of sequence B, 
the type effective in reproduction. ‘It might appear that this is 
virtually homotypic, since quantitative, and therefore mainly if 
not in detail in agreement with JuEL’s theory. Possibly this is 
true, but number and character of chromosomes do not correspond 
with those usual in homotypic divisions. Sex as a factor is com- 
pletely absent in homotypic division, while here it is present, in 
abeyance of course, but potential. This is evidenced by (a 
chromosome number, (6) pairing of prochromosomes, (c) synaptic 
pairing (albeit delayed) of the cuboids, (d) occasional cases of true 
reduction in pollen and presumably in geod sac. It seems, 
therefore, that the designation “‘ameiosis,” or ‘‘amiosis,’’ proposed 
by Sears in 1917 (23), and indicating a type of maturation which 
obviates necessity for subsequent fertilization, is to be preferred to. 
“‘homotypic mitosis,” a term of very explicit implications. 
2. The parasynaptic interpretation of reduction division, so far 
as normal sexual species of Taraxacum are concerned, was favored 
by the work of JuEL and Osawa, since both workers noted a duality 
of spireme thread in meiotic and none in ameiotic plants. Closer 
scrutiny previous to segmentation has revealed a duality in the 
segmenting thread, while precise counts have indicated that this 
