No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 
333 
Bohmig (’93), Rhodope veranii: the single nucleolus in older 
eggs contains one or several vacuoles. 
Brauer (’93) investigated the spermatogenesis of Ascaris 
megalocephala: there is one homogeneous nucleolus in the 
spermatogonium, which becomes smaller in the spermatocyte 
and often evinces a large vacuole. The nucleolus is smaller 
than the centrosome (which is at this stage enclosed in the 
nucleus), and stains differently from the latter. 
Brooks (’93), Salpa: the single large nucleolus of the ovarian 
ovum “ is suspended near the center of the nucleus by a net¬ 
work of fine threads.” 
Fick (’93) studied the maturation of the egg of the Axolotl. 
In the germinal vesicle lies a group of nucleoli, which vary in 
size from 3 /x to i6/x ; some contain a single vacuole, and some 
stain more deeply than others. The greater number of them 
disappear at the time of the longitudinal division of the chro¬ 
mosomes, though a few may remain in the yolk for a certain 
time. “Bei den Nucleolen des Keimblaschens liegt es sehr 
nahe mit Strasburger und Pfitzner daran zu denken, dass sie 
vielleicht eine Art Reservestoffbehalter darstellen ” ; further, 
he holds that the nucleoli “ in einer allerdings noch nicht auf- 
geklarten Beziehung zu den Veranderungen des Chromatins 
stehen, da sie bei der Ausbildung der Chromosomen fur die 
erste Spindel vollstandig verschwinden.” 
Frenzel (’93a) studied the nucleoli of various Gregarines. 
In Gregarina statirae the single nucleolus, which he terms 
“ Morulit,” appears “ eigenthiimlich glanzend mit einem 
schwach gelblichen Schimmer und dabei an der Oberflache 
rauh und warzig-runzelig. ... In seinen Reaktionen verhalt 
er sich an alien Orten ahnlich wie Nuklein.” In G. bergi a 
single Morulit is present. In the embryo of Pyxinia crystalligera 
there is a single Morulit; in older individuals the nucleus 
“ enthalt mehrere helle, klare, glattrandige und lebhaft glan- 
zende Nucleoli ... die oft noch einen Fliissigkeitsraum im 
Innern bergen.” In Gregarina port uni, Callyntrochlamys , and 
Aggregataportunidarum there are several nucleoli in the nucleus. 
Frenzel (’93b) hepatopancreas cells of Astacus: in the fat 
and ferment cells a single nucleolus is present ; in the amitosis 
