No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 363 
together with the nucleoli correspond to the macronucleus of 
the Infusoria. 
Gerould (’96), ovarial eggs of Caudina: in the youngest ova 
there are numerous peripheral nucleoli; these increase in size 
as the nucleus grows, and subsequently each contains a vacuole, 
but they are always close to the nuclear membrane. 
Greenwood (’96), macronucleus of Carchesium polypinum: 
the nucleoli (“ protomacrosomes,” in distinction to the “pro- 
tomicrosomes,” or chromatin granules) are numerous and 
vacuolated, and stain like true metazoan nucleoli. They vary 
in size and form, and are probably amoeboid, though this point 
could not be determined in the living nucleus, which is first 
rendered visible by reagents. The vacuoles are fluid accumula¬ 
tions, and arise first in the center of the nucleolus. “No 
vacuoles surround the macrosomes of Carchesium at any time, 
nor do they ever show general increase of fluidity or swelling 
such as might accompany the penetration through them of some 
secretion from without ; . . . the deposition of vacuolar fluid is 
centrifugal ; . . . thus the macrosome may become a bladder¬ 
like or honey-combed structure, its residual solid (?) forming a 
well-defined membrane-like investment for fluid contents.” 
Henneguy (’96) distinguishes true and false nucleoli (the 
latter being “ noeuds du reseau,” in the sense of O. Hertwig, 
’92). He reviews the observations upon nucleoli made by 
several previous authors. 
R. Hertwig (’96), unfecundated ova of echinoderms poisoned 
with strychnine : the nucleoli vanish within the nucleus as the 
chromosomes appear. “ Meine eigenen Untersuchungen lassen 
es mir ausgeschlossen erscheinen, dass im Ei der Seeigel Nu- 
cleolen und Centrosomen irgend etwas mit einander zu thun 
haben. . . . Dagegen ergeben sich unzweifelhafte Beziehungen 
der Nucleoli zur Entwicklung der Chromosomen. . . . Dieses 
Wechselverhaltniss ist nun nicht so zu verstehen, als ware das 
gesammte Material der Chromosomen in den Nucleoli enthalten. 
Dagegen spricht die geringe Masse der Nucleolar-Substanz und 
ihr verschiedenes Verhalten den iiblichen Chromatin-Farbungs- 
mitteln gegeniiber. . . . Die Nucleolen konnen somit den 
Chromosomen ein zur endgiiltigen Fertigstellung nothwendiges 
