A critical study of the cytology of Crepis virens. 
133 
presenting the approximation of two entire (homologous) somatic 
chromosomes. 
The telosynaptic interpretation of the heterotype prophases is en- 
dorsed both by Goldschjiidt (17) and by Häcker (22). They consider 
the paired arrangement in the chromatic contents of the heterotype pro- 
phases to be the expression of the future longitudinal fission. Häcker 
States that they are not the associations of “ursprünglich selbständiger 
Elemente” but the “Anlage eines frühzeitig gespaltenen Spirems” (p. 78). 
Telosynaptists and parasynaptists are for the most part in agreement 
tvith regard to the evolution of the somatic mitosis. They recognise 
the Separation of the longitudinal halves of each chromosome during 
the telophase, theh- reassociation during the ensuing prophase, and 
their gradual condensation until each longitudinal half becomes a 
daughter chromosome. Telosynaptists place the same interpretation on 
the parallel and condensing portions of the paired nuclear contents of 
the heterotype presynaptic prophases, whereas the parasynaptists regard 
these paired chromatic portions as representing the association in pairs of 
homologous chromosomes. The telosynaptists base their views largely 
on the dose similarity between the somatic and heterotypic presynaptic 
prophases, which makes it difficult to beheve that the paired portions 
can have a different significance in the two mitoses. Again, in those 
forms where there is no interkinetal rest between the last premeiotic mi- 
tosis and the meiotic prophase, it is possible to trace the origin of the 
paired portions of the heterotype prophases as Segments of the longi- 
tudinaUy spht chromosomes of the preceding telophase. Fraser and 
Snell (14) have contributed an important piece of evidence in favour 
of the telosynaptic view. They have compared the heterotype prophases 
with those of the gametophyte where “there is no question of the as- 
sociation of paternal and maternal structures since only a single set of 
chromosomes is present. But in the poUen-grain, exactly as in the ceUs 
of the root or flower, a double reticulum was observed, and here also the 
first evidence of duplication appears in the late telophase” (p. 848). 
On the other hand, parasjmaptists base their views largely on the 
similarity between the paFed portions of the nuclear contents of the 
presynaptic and post synaptic phases. Their interpretation of the paired 
portions of the heterotype prophases involves a complete rearrangement 
of the elements of the chromosomes of the last premeiotic telophase. 
Frisendahl (15) has shovni that the different significance attached 
to the parallehsms of the heterotype presynaptic prophases as compared 
to those of the somatic prophases, is revealed by the fact that whereas 
