672 
J. P. Munson 
Munson (62) also published in this year an account of the yolk nucleus 
in tke egg of the tortoise, Clemmys marmorata, showing in the cytoplasm 
a constant body in which were evidences of a center and aster, besides 
other masses of metaplasm scattered throughout the egg. 
An important contribution was made by LoYEz(53b) in 1906. He 
published figures of the yolk nucleus of Anguis fragilis, Tropidonotus 
viperinas, Viper a aspis, Testudo graeca, Cistudo Europaea, Crocodilus, 
Coccothraustes chloris, Emboriza citrinella, Passer domesticus, Polyboroides 
M adagascaricnsis. 
In 1907 Lams (53) published very interesting observations on am- 
phibian ova. He shows many fine figures of dividing oogonia with centro- 
some and sphere, the sphere being apparently continuous with the yolk 
nucleus of the oocyte. 
Finally King (40) published a paper in 1908 in which she has this to 
say about the yolk nucleus in egg of Bufo : “In the egg of Bufo it is possible 
to trace the anlage of the yolk nuclei back to the primordial germ cells”. 
II. Original Observations and Inferences. 
The Egg of the Tortoise. The oogonia lie in the connective tissue 
stroma of the ovary , pl. XXIX, fig. 1. In all of these oogonia, there is avery 
distinct body in the cytoplasm, always spherical, nearly one half the size 
of the nucleus. It often shows indications of concentric circles, with a 
clear area in the middle; or eise a central granule suggesting a centrosome. 
The body is connected with the nucleus, by a circle of larger cyto- 
microsomes, enclosing an area which differs somewhat from the cyto- 
plasm ontside this circle. The oogonia finally divide, and produce a liest 
of several smaller cells, one of which becomes the oocyte or egg; the others, 
the follicle cells. 
Düring this division, the large, conspicuoits centrosome is greatly 
reduced and appears as a rnere dot in the cytoplasm of the daughter cells. 
As one of these cells begins to increase more rapidly than those destined 
to become follicle cells, the centrosome becomes more and more c.onspicuous, 
fig. 4. It consists of a central circle of microsomes, enclosing a central 
granule, fig. 7, the centrosome. 
This original centrosome becomes embedded in, and consequently 
obscured by, a substance produced or arising in the neighborhood of the 
germinal vesicle. It often presents the appearance of a sticky, amorphous 
substance, staining differently from the contents of the germinal vesicle, 
and differently from any other part of the cytoplasm. I have called this 
