MONTGOMERY. 
[Vol. XV. 
276 
Eimer (’73), nervous system of Beroe: each nucleus contains 
one large nucleolus. “ Aufmerksamer Beobachtung kann es 
nicht entgehen, dass jede Epithelzelle von einer Primitiv- 
fibrille versorgt wird. ... Ich kann nur so viel sagen, dass 
ich dieselbe [Primitivfibrille] stets auf das Centrum des Kerns 
zugerichtet sah, so dass ich zu der Ansicht hinneige, es werde 
sich spaterhin ihre Endigung im Kernkorperchen feststellen 
lassen.” 
Fol (’73) noticed in the egg of Geryonia fimgiformis one 
large nucleolus, containing one large, or several smaller 
vacuoles. 
Auerbach (’74). This important paper I have been unable 
to consult in the original, and quote from citations by 
R. Hertwig (’76) and Flemming (’82). According to Auerbach 
the nucleus is originally a vacuole in the protoplasm, around 
which a layer of the latter becomes differentiated to form a 
nuclear membrane. In this vacuole a nucleolus appears 
later, being derived from the protoplasm, either by a separa¬ 
tion of particles from the nuclear membrane or is produced 
out of those protoplasmic particles which had penetrated 
from the protoplasm into the original vacuole. He distin¬ 
guishes “ enucleolar,” “ uninucleolar,” and “ multinucleolar ” 
nuclei, the first being the more primitive state. The nucleo¬ 
lus has the value of an elementary organism : as long as it 
is homogeneous, it is comparable to a cytode ; when a vacu¬ 
ole appears in it, the latter stands in the same relation to 
the nucleolus as this does to the nucleus, so that that vacuole 
may be considered the nucleus (“Kern”) of the nucleolus. 
The original single nucleolus can divide into numerous nucle¬ 
oli, and the latter, by the disappearance of the nuclear 
membrane, become free, and each develops into a separate 
cell. Auerbach considers this theory as “eine vorlaufige, 
noch mit Vorbehalt aufzustellende und weiter zu priifende.” 
A. Brandt (’74) observed in life (in the blood fluid) slow 
amoeboid motions of the single nucleolus of the egg of Blatta. 
Flemming (’74) investigated the egg of Anodonta. In young 
eggs the nucleolus consists of two apposed spheres of equal 
diameter; in larger eggs one of these spheres is much larger 
