670 
J. P. Munson 
Korschelt (46) had shown in 1889 tliat, in the egg of insects, there 
is a mass of stainable granules in the neighborhood of the germinal vesicle, 
and in 1892, Monticelli (60) announced the finding of a yolk nucleus 
in the ovum of Trematodes. 
In 1983, Henneguy (32) wrote; “Chez les Rats, äges de quelques 
semaines, dont les ovaires ne renferment que des ovules peu avances, on 
constate, apres fixation par le liquide de Flemjung, que tous les jeunes 
ovules contiennent, a cöte du vesicule germinative, un petit corps arrondi, 
nettement circonscrit et un peu plus colore que le reste du protoplasme 
ovulaire.” 
An account of an irregulär body in the cytoplasm of the egg of a fish 
was published in 1894 by Hubbard (37). 
In 1893, Mertens (58) published observations on the egg of birds 
and m amm als. He shows the presence in the egg of birds, including the 
fowl, a large spherical, granulär body about the size of the nueleus, and 
oecupying a position in the center of the egg. He found the same in the 
egg of a young eat and in a young human ovum. In the center of some 
of these, he found a deeply staining granule suggesting a centrosome in 
the midst of an attraction spliere. 
The term yolk nueleus was applied by Calions (17) to an irregulär 
mass of granules partly surrounding the germinal vesicle of the egg of 
Lumbricus. 
It is clear tliat the definite, spherical body originally described as 
the yolk nueleus in spiders and myriapods, and described again in 1893 
by Balbiani (4) and by Henneguy (32), lias now become thoroughly 
mixed up with any granulär substance in the cytoplasm. When nothing 
more definite is found, even yolk granules are called yolk nucleus. 
Foot in the following year, published observations on eggs of Allo- 
lobophora, with figures showing amorphous substances appearing as 
irregulär patches throughout the egg cytoplasm, and described as more 
or less fluid, and capable of flowing from place to place. It was supposed 
to be allied to the polar rings observed by Whitman. 
In 1897, Nemec (66) published an account of the yolk nucleus in 
Pohjzonium. In the young eggs, it is represented as a granulär mass, in 
which there is a granule, the whole forming a cap partly enclosing the 
nucleus. Later this, he affirms, is differentiated into two distinct bodies, 
one of which assumes the form ( f an aster. 
Munson (61) published in 1898, an account of the history of the 
ovarian egg of IÄmulus, in which he showed the various stages of the egg 
from the beginning in the germinal epithelium to the period of maturity, 
