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MONTGOMERY. 
[Vol. XV. 
a clear, structureless space within the nucleus ; at first homo¬ 
geneous, it later contains from one to five unstaining “ Korper- 
chen,” which he thinks are not vacuoles, on account of their 
refractibility. In the amitotic division of those nuclei which 
degenerate and eventually become absorbed by a definitive egg 
cell, division of the nucleolus precedes that of the nucleus. 
Floderus (’ 96 ) studied the maturation and embryonal develop¬ 
ment of various Tunicata. A “ Hauptnucleolus ” and “ Neben¬ 
nucleoli” are present. The former is homogeneous in only 
very young cells, and later differentiates into two different sub¬ 
stances : (i) a refractive, larger portion, which encloses (2) a 
less-refractive, paler portion. He considers the small vacuoles 
of the nucleoli to be “ Kunstprodukte,” though the large one is 
normal. “Nicht selten findet man in dieser grossen, allem 
Anscheine nach mit Fliissigkeit erfiillten Hohlung eine Anzahl 
fester, lichtbrechender Kornchen, vielleicht Coagulationspro- 
dukte, die wahrscheinlich bei der Fixierung entstanden sind.” 
As a rule there is one, but sometimes two “ Nebennucleoli ” 
in most though not all eggs ; these rarely attain half the 
diameter of the “ Hauptnucleolus,” and appear in the germinal 
vesicle shortly before the yolk granules arise in the cytoplasm; 
they are similar to, but paler than, the refractive portion 
of the large nucleolus. The “Nebennucleoli” are absent in 
Clavelina ; they probably arise by gemmation from the “ Haupt¬ 
nucleolus,” and he figures to this effect a lobular “ Hauptnu¬ 
cleolus.” In the cytoplasm of the ova of Styelopsis and Ciona 
(but not Clavelina and Corella) certain spherical “ intravitelline 
Korper” occur, usually one to a cell, and frequently close to 
the nuclear membrane ; in size and staining reactions these are 
similar to the “ Nebennucleoli,” and, following Roule, “ sehe ich 
mich genothigt, anzunehmen, dass sie von Nebennucleolen 
herriihren, die aus dem Kern des Eies in den Dotter hinausge- 
wandert sind,” thereby supposing that they press out through 
a preliminarily produced pore in the nuclear membrane, and 
that the larger intravitelline bodies are probably fused masses 
of smaller ones. In accord with Henneguy (’ 93 ) and Roule he 
considers the intravitelline bodies not as “ Dotterkerne ” nor 
astrospheres, but as atavistic or rudimentary organs, which 
