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[Vol. XV. 
Substanz ist. Das oben eingehend besprochene Verhalten der 
Embryonalkerne liess dagegen eine ganz andere Auffassung zu, 
obwohl es auch bei diesen allerdings abnormer Weise vorkommt, 
dass neben den bereits gebildeten Chromosomen (sogar in der 
angelegten Spindel) der Kernkorper noch vorhanden ist. . . . 
Was die erwahnten Verschiedenheiten des Verhaltens der 
Nucleolen in dem Ei- und Embryonalzellen betrifft, so liessen 
sich diese vielleicht durch die recht verschiedenartige Ausbil- 
dung und Funktion der Kerne in den beiderlei Zellen erklaren.” 
Lauterborn (’95a), nuclear division of Ceratium hirundinella: 
from one to four oval nucleoli are present and are frequently 
apposed to the nuclear membrane. One nucleolus is still 
present in the spirem stage (the mitosis advances no further 
than this); but he was unable to decide whether this nucleolus 
divides into two. 
Lauterborn (’95b), Multicilia : each nucleus contains a rela¬ 
tively large nucleolus, which frequently shows a “netzig- 
wabige” structure. 
Macallum (’95) concludes that less iron is contained in the 
nucleolus than in the chromatin, as is shown by its lighter stain 
with haematoxylin. Nucleoli “are always attached to the 
chromatin network, and sometimes there appears about them a 
membrane derived from, and continuous with, the fibrils with 
which they are connected.” In a nucleus of a gland cell from 
the kidney or liver of Necturus “ which is passing into the 
mitotic phase, the nucleolar body disappears, apparently by 
solution into the chromatin threads, for in the nucleus of a renal 
cell, in which the meridional disposition of the chromatin 
filaments obtained preparatory to the formation of the loops, I 
saw, attached to one of the filaments and partly embraced by 
its substance, what appeared to be the remains of such a body.” 
The nucleoli of the amphibian ovum are derived from the 
chromatin of the nuclear reticulum. In support of his previous 
observations (’91) he adds, “ that the iron in the cytoplasm of 
the ovum makes its appearance only after the solution of the 
peripheral nucleoli commences.” In plant cells ( Erythronium) 
there are at least three kinds of nucleoli : the first stain 
intensely with eosin ; the second are composed of chromatin ; 
