668 
J. P. Munson 
In the same year Nussbaum (67) found bodies of various shapes in 
the cytoplasm of pancreas cells of Salamandra maculosa. Ileferring to 
these he says: “Dagegen wird man den Nebenkern der Drüsenzellen wohl 
mit dem von Wittich entdeckten Dotterkern der Eier, dem durch von 
la Valette St. George zuerst bekannt gewordenen Nebenkern der 
Spermatocyten, den von Leydig aus der Epidermis von Peloibates-Laxven 
beschriebenen Bildungen in eine Kategorie bringen dürfen.” 
The next year Sarasin (79) desc-ribed a body in eggs of reptiles, con- 
sisting of a clear vesicle surrounded by little dark granules. He did not 
call it a yolk nucleus but only “Kern”. He eonsidered it to be a “Dotter- 
herd” — a substance which transforins the secretion of the foüicle cells 
into vitelline elements. Eimer (25) had described a similar body in the 
green lizard — a large body in the center of the cytoplasm of small eggs. 
He called it “Dotterkern”. Two vitelline bodies were represented in a 
clear mass. From the latter he claimed fraginents were detached. 
Oscar Schultze (83), in 1887 figured and described a body in the 
cytoplasm of the frog’s egg, as the yolk nucleus. It was close to the ger- 
minal vesicle, crescentshaped and resembled archoplasm. 
In a series of articles fi'om 1864 to 1893, Balbiani (3) has given descrip- 
tions and figures of the yolk nucleus in eggs of various animals, including 
Tegeneria, Clubiona, Geophilus, skate, frog, estrel, hen, cow and the human 
ovum. In nearly all cases , it is represented as a spherical vesicle contain- 
ing granules and surrounded either by a circle of granules, or by a layer 
of concentric fibers. In Geophilus, he represents it as a sphere surrounded 
by radial striations like the rays of an aster, but he also shows in the same 
egg, other large granulär masses in the cytoplasm. 
From the year 1893, up to the present time, observations on the yolk 
nucleus have been numerous ; and in many cases, the granulär, amorphous 
bodies in connection with it, or included in the cytoplasm of the same 
egg, have received more attention. 
As early as 1878 Whitman (99) described amorphous substances in 
the egg of Clepsäne, which owing to its position in the egg, he called 
polar rings. 
In 1886, Will (94) found the yolk nucleus in eggs of insects, which, 
however, had already been studied by Balbiani in Apliids and in 
Hymenoptera. 
In the following year Blochmann (12) published a paper in which 
he mentions something in the egg of Camponotus ligniperda, suggesting 
the yolk nucleus. These are his words: “In den Eiern, die sich ungefähr 
in der Mitte der Eiröhre finden, bemerkt man eine sehr auffallende faserige 
