30 
Wager . — The Nucleolus and Nuclear Division 
Literature. 
In the following brief account of the literature, reference is only made 
to the more important papers in which the relations of the nucleolus to 
the chromatin and chromosomes are dealt with, and more especially to those 
papers published since 1897. An excellent summary of the whole of 
the literature on nucleoli, down to 1897, is given by Montgomery in his 
valuable memoir on the Morphology of the Nucleolus 1 . 
According to Flemming 2 the nucleolus is a special organ of the 
nucleus or cell for the collection or elaboration of chromatin. It does not 
actually consist of chromatin (or nuclein), but of a substance in which the 
chromatin is elaborated, or, it may be, of a homogeneous substance which 
may be a chemical modification of chromatin or a preliminary stage in its 
formation. It possesses a definite form, but with no membrane around it, 
and it may be vacuolate with fluid contents in the vacuoles. 
Strasburger 3 regarded the nucleolus as an inert mass consisting of 
a reserve substance or substances, allied to chromatin, for the formation of 
the chromosomes. During division the nucleoli become dissolved in the 
nuclear sap and are then taken up into the nuclear thread, to reappear again 
in the chromatin-network of the daughter-nuclei. 
Pfitzner 4 , Guignard 5 , Went 6 , and others give expression to similar views. 
Strasburger, in his more recent memoirs 7 , adopts a different view from 
that just stated. He now believes that the chromatin is contained in the 
nuclear sap, and that one must look for its origin in the cytoplasm and not 
in the nucleolus. The nucleolar substance serves for the building up of 
the spindle. The evidence for this appears to be the complete or partial 
disappearance of the nucleolus immediately preceding the formation of the 
spindle ; the active and quantitative condition of the kinoplasm rises or 
sinks as the nucleolus dissolves or reappears, and the solution of the 
nucleolus is followed by the highest point of spindle-development. He 
brings forward the observations of Nemec, who states that the kinoplasm 
is directly transformed into nucleoli, and that granules which show the 
peculiarities of nucleoli arise at the poles of the division-figure through 
transformation of the spindle-threads. Their appearance is especially due 
1 Jour, of Morph, xv, 1899. 
2 Zellsubstanz, Kern- nnd Zelltheilung. Leipzig, 1882. 
3 Ueber den Theilungsvorgang der Zellkeme und das Verhaltniss der Kerntheilung zur Zell- 
theilung, Arch. f. mikr. Anat., xxi, 1882. Die Controversen der indirekten Kerntheilung, Arch, 
f. mikr. Anat., xxiii, 1884. 
4 Beitrage zur Lehre vom Bau des Zellkerns und seinen Theilungserscheinungen, Arch. f. mikr. 
Anat., xxii, 1883. 
* 5 Nouvelles recherches, &c., Ann. Sci. Nat., Bot., Ser. 6, xx, i88"5. 
6 Beobachtungen iiber Kern- und Zelltheilung, Ber. d. deutsch. Bot. Gesell., v, 1887. 
7 Karyokinetische Probleme, Jahr. f. wiss. Bot., xxviii, 1895. Ueber Reduktionstheilung, 
Spindelbildung, Centrosomen und Cilienbildner im Pflanzenreich. Jena, 1900. 
