98 
L. Digby 
Laibach (26) subsequently confirmecl Rosenberg’s observatious 
regarcling the resting nuclei of Capsella Bursa-pastoris, but he cloes not 
oonsider that the chromatic aggregations actually represent chi'omo- 
somes, but that they coiistitute clu-omosome centres — “es kann sich 
vielmehr in den Körnern bloß um Zentren handehi, um die zwar der 
größte Teil der Substanz der Chromosomen angesammelt ist, daß aber 
nicht die ganze Substanz der Chromosomen m ihnen gespeichert ist...” 
(p. 198). 
In 1904 Strasburger (52) showed, m the presynaptic stages of 
Tlialictmm purpurascens and in Galtonia candicans, that the chromatm 
forms ‘Körnchen’ which collect at definite centres ‘Gamozentren’, cor- 
responding to the number of the future heterotype chromosomes. He 
called the ‘Chroniatinkörner’ ‘Gamosomes’. The ‘Gamosomes’ paii- to 
form a ‘Zygosom’, and each Zygosom gives rise to a bivalent chromo- 
some. 
A subsequeiit paper by Strasburger (53) which was published 
shnultaneously with those by Overton (40), Miyake (33) and Allen (1) 
brought the question of the permanence of chromosomes into still greater 
prominence. In this paper Strasburger States that he could not 
definitely count the “dichteren Partien im Gerüstw'erk” (p. 7) of the 
resting somatic nuclei either in Galtonia candicans or in Funkia siebol- 
diana as the “Stellen” are too indefinite m outline and too variable m 
size (p. 13). He endorsed his previous observatious with regard to the 
pairing of the ‘gamosomes’ to form the ‘zygosonies’ in the presynaptic 
phases. Miyake (33) likewise described ‘zygosonies’ in the heterotype 
prophases of Galtonia candicans, whilst m later investigations by Gre- 
GOiRE (20) and the author (9) no definite zygosonies could be recognised. 
It was Overton (40) who first introduced the term ‘prochromo- 
some’ into literature. He believes that in well nourished nuclei “mag 
ein Überfluß an Chromatin vorhanden sein, der um die Zentren gesammelt 
blieb, ohne sich auf das Netzwerk der Chromosomen zu verteilen. Um 
diese Zentren sammelt sich auclL das anderweitige Chromatin, wenn 
die ZeUe sich zur Teilung anschickt. Diese Chromatinansammlungen 
scheinen mm ein fast sicherer Beweis für die Fortdauer eines Chroniosomen- 
teils, somit auch für die Individualität der Chromosomen zu sein” (p. 124). 
In Thalictnim pnirparascens, CaJycanthus floridiis, Campanula grandis, 
and Helleboms foetidus he found ‘jirochromosomes’ in the resting somatic 
nuclei, and these reappear in the prenieiotic resting nuclei, and pair as 
they pass into synapsis. In a later paper (41) he substantiated these 
views with certain modifications. 
