228 TRANSACTIONS OF THE [may 13, 
of the colors—the chromatin and yolk-nucleus were stained red 
and the cytoplasm green. Other differential stains were used 
and all gave similar results. After Flemming’s triple stain the 
yolk nucleus and chromatin were purple; the cytoplasm and 
nucleolus had an orange tint. After borax carmine and Lyons 
blue the yolk-nucleus and chromatin had the bright red stain of 
the carmme. - 
The only conclusion that can be drawn from these experi- 
ments and from the morphological evidence of the origin of the 
yolk-nucleus is that this element of the egg cell of Lumbricus 
originates as chromatin. The micro-chemical reactions, how- 
ever, show that it does not retain the chemical composition of 
the chromatin. As the egg grows and as the yolk-nucleus dis- 
integrates, the several parts gradually lose their affinity for the 
nuclear stains, and gradually acquire that of the cytoplasm. 
In some stages the parts of the yolk-nucleus have no definite 
stain, while in one or two cases some portions of the disinte- 
grated body were stained with the cytoplasmic colors, while 
others in the same egg were colored like the nucleus. 
One other observation remains to be noted. As the eggs de- 
velop into the germinal vesicle stage, the nucleus gradually be- 
comes filled with minute particles which stain like the cyto- 
plasm, while the chromatin is aggregated into rather a dense 
mass at one part of the germinal vesicle (fig. 5). These parti- 
cles within the nucleus acquire the cytoplasmic stain at the 
same stage as the parts of the yolk-nucleus and it is probable 
that they are of the same substance. 
To conclude with a few words regarding the fate of the yolk- 
nucleus. Thompson (’59), Waldeyer (’70) and Legge (’87) 
thought that it disappeared completely before the egg is ripe. 
Scifer (80) asserted that it entered into the formation of the 
folliclecells. Jatta (’82), that it became evenly distributed over 
the egg. lijimi, that it served as nutritive material (yolk). 
Korschelt (’89) maintained that it breaks up into small balls, 
which wander into the germinal vesicle. Jordan (’93) thought 
that it serves as food substance. Lavdowsky (’94) held that 
the yolk plates are taken bodily into the nucleus where they 
form chromatin. In Lumbricus the yolk-nucleus disintegrates, 
and the parts become homogeneous in appearance, and then en- 
large to form the great yolk plates. 
The results of these observations on the yolk-nucleus may 
finally be thus summarized: The yolk-nucleus is chromatin in 
the form of a mass of granules; this granular mass disintegrates 
and the parts form the yolk plates of the egg after undergoing 
change in their chemical composition. 
CotumBIA CoLLEGE, May, 1895. 
