A critical study of the cytology of Crepis virens. 
By 
L. Digby. 
With plates VIII to X. 
The view that the permanence of chromosomes, froni one cell genera- 
tion to another, may be establishecl by the presence of chromatic bodies 
or ‘prochromosomes’ in resting interkmetal iiuclei, has evoked much 
Interest, disciission, and criticism, during the last few years. A study 
of the literature dealing with the siibject reveals considerable lack of 
unanimity in the conclusions reached by different writers. It is there- 
fore proposed, in this introduction, to sketch briefly the development 
of the arguments, and to outhne the different vievs held Ijy cytologists. 
Further detail will be discussed at the end of the paper following the 
description of the mitoses of Crepis virens. 
Auerbach (2) working on animal cells foimd that by iising a double 
stain, he could distinguish the nucleolus from certain other sniaU bodies 
present in the resting nucleus which he termed ‘kyanophile Nukleolen’. 
These are the chromatic aggregations or ‘prochromosomes’ of later in- 
vestigators. 
Kosen (43) recognised the ‘kyanophile nucleoli’ in vegetative nuclei 
of plants, and called them ‘pseudo-nucleoli’ as opposed to the true, or 
‘eu-nucleoli’. 
Zacharias (63) in Cucurbita Pepo ascertained that the ‘pseudo- 
nucleoli’ were chromatic, “nucleinhaltiger Körper” (p. 221). 
Some years later Rosenberg (44) identified these bodies in Capselia 
Bursa-pastoris, in Zostera marina and in Calendula sp. and described 
them as being chromatic in staining reaction, and according fairly closely 
in number with the chromosomes characteristic of the particular plant 
concerned. 
Archiv f. Zellforschung. XII. 
7 
