37 
in the Root-Apex of Phaseolus . 
up into chromosomes. The nucleolar remnants which may remain in 
many cells, after the formation of the chromosomes, have no longer the 
characteristics of the nucleolus as presented before karyokinesis. They 
have become reduced in volume and in capacity for stains. This means 
that the chromatin-like substance has been subtracted from the nucleolus 
to build up the chromosomes, leaving the plastin which is employed in 
another manner, as in the formation of spindle-fibres and the new cell-wall. 
As the nucleoli are reconstructed during the anaphase, they become 
centres of attraction, not only for plastin, which is taken up from the nuclear 
sap, but also in part for chromatin, which is taken up from the nuclear 
thread. The differences which have been observed in the capacity of nucleoli 
for stains can be explained by the fact that they contain varying quantities 
of the two substances (see also Hertwig, loc. cit.). Without impugning the 
constancy of the characteristics of the nucleoli and chromosomes, ‘ non vi 
ha dubbio che gli uni e gli altri siano organi di una certa mutualita e 
transitorieta, e che come avviene dissoluzione di nucleoli o pirenolisi in seno 
al nucleo, altrettanto si possa dire di dissoluzione della cromatina, o di 
cromatolisi'. Chromatolysis ought not then to be regarded merely as an 
abnormal or pathological phenomenon, but it represents a normal condition, 
sine qua non , of the evolution of the cell. 
Cavaras conclusions are combated by Longo 1 , who says that from 
his observations the nucleolus is not formed of two distinct substances, and 
that the so-called plastin portion of the nucleolus represents only a 
vacuolization. 
Buscalioni % also concludes that there is no connexion between 
the formation of the chromosomes and the disappearance of the 
nucleoli. 
Bradley M. Davis 3 shows that in the tetraspore mother-cells of Corallina 
officinale the chromatin is scattered in a finely divided state in the nucleus, 
and that a linin-network is wanting. Each nucleus contains a single 
nucleolus which stains differently from the chromatin-granules. After 
division the chromosomes fuse together into a large deeply stained body 
on the surface of the prominent centrospheres. A nuclear membrane is 
formed and then the nucleolus reappears, at first smaller than the chromatin 
body, but afterwards becoming larger. The chromatin body then begins 
to fragment into a number of minute granules surrounding the single con- 
spicuous nucleolus, 
1 Existe cromatolisi nei nuclei normali vegetali ? Rendiconti della R. Acc. dei Lincei, 7 a ser., 
v, 1898. Contribuzione alia cromatolisi (picnosi) nei nuclei vegetali. Estratto dal vol. 9 0 degl’ 
Ann. del R. Istit. Bot. di Roma. 
2 Osservazioni e ricerche sulla cellula vegetale. Ann. del R. Istit. Bot. di Roma, vii, 1898. 
See Bot. Cent., lxxix, 1899. 
3 Kerntheilung in der Tetrasporenmutterzelle bei Corallina officinalis, L., var. mediterranea. 
Ber. d. deut. Bot. Gesell., xvi, 1898. 
