A critical study of the cytology ol Crepis virens. 
129 
The controversial matter concerns the definite chromatic bodies 
found in certain resting nuclei; do they represent chromosomes, and thus 
testify to the indmduaüty of chromosomes throughout interkinesis, or 
are they mere aggregations of chromatm? 
In the introduction, the obsercations and views of certain investiga- 
tors have been briefly recorded. At first sight it would appear as if 
their divergent resiüts could not be coordinated. Contradictory data have 
even been derived from the examtnation of identical tissues. Never- 
theless, if the matter be analysed, some reasons for the diversity of ex- 
pressed opinion can be found. 
In the first place, it has been shown by Rosexberg (44) that resting 
nuclei may be broadly divided into two classes ; the Fritülaria-tj^e having 
a fine reticulum with somewhat indefinite chromatic aggregations, and the 
Capsella-type having definite chromatic bodies. Many of the Mono- 
cotyledons belong to the first type, and of the Dicotyledons to the 
second. Rosexberg (45) in this connnection has written “daß besonders 
unter den Monokotyledonen die Feststellung der Zahl der ‘Chromatin- 
kliimpchen’ mit großen Schwierigkeiten verbunden ist und in vielen Fällen 
überhaupt nicht gelingt” (p. 401). 
The matter is further comphcated by the fact that resting nuclei of 
any one animal or plant may exhibit varied degrees of concentration 
of their chromatic contents, and in fact both the FritUlaria and CapseUa 
types may be present in the same individual. It is this circumstance which 
may account for the fundamentally different observations recorded. In 
the same animal or plant the chromatic nuclear contents may be more or 
less concentrated into definite aggregations and these may approximate 
in number to the chromosomes, or they may be distributed throughout 
the reticulum as smaU deeply staining granules. It has already been noted 
that Gregoire (20) and Mottier (35 and 36) have described two distinct 
types of presynaptic phases in various plants (see pp. 125 & 126) which are 
characterised by the relative distribution of the chromatic contents. 
Moreover, this phenomenon undoubtedly explains the different 
results arrived at by Rosexberg (46) and by Beer (3) with regard to 
the resting nuclei of Crepis virens. Rosexberg observed the definite 
chromatic aggregation or ‘prochromosome’ type, whereas Beer saw that 
of the finer chromatic distribution. In this investigation both series 
of presynaptic prophases have been found in the same capitulum, but not 
in the same bud. In a section of a capitulum the resting nuclei, prior 
to the heterotype prophase, may show definite chromatic bodies in one 
bud, whilst in another they may have a fine reticulate structure. The 
.Archiv f. Zellforschung. XK. 9 
