No. 1.] YOLK-NUCLEUS AND POLAR RINGS. 5 
greatly increases as the egg grows, and can be traced (by 
the sharp contrast of color) step by step during the develop- 
ment, fertilization, and cleavage. It is present at the chief 
points of activity in the cell: it is in the spindle, it forms the 
fertilization cone and the archoplasm of both sperm and egg 
attraction-spheres ; and at the pro-nuclear stage a part of it 
is aggregated at both poles of the egg, forming the structures 
known as the polar rings. For this blue substance I shall 
retain the term employed by Boveri in a far more limited 
sense — the term archoplasm. 
In no case where the method has been properly applied have 
I found a cell in the resting stage, — that is, a cell containing 
nucleus, nucleolus, and cytoplasm,— without being able to 
recognize at least a trace of the archoplasm, the cell often 
being so small as to make it impossible to decide whether it 
belongs to the earlier or to the final generation of odgonia. 
As growing oécytes are found close to the stem of the ovary, 
surrounded by dividing odgonia, the locality of the cell is 
not a trustworthy indication of the stage to which it 
belongs.! 
In Fig. 2 we have an older odcyte, with the archoplasm 
increased in proportion to the rest of the cell. 
1In the spermatogonia of Salamander mac., Meves finds masses of granular 
substance, which he identifies with the “ yolk-nucleus ” of other authors and with the 
attraction-sphere. F. Meves, “ Ueber eine Metamorphose der Attractionssphare 
in den Spermatogonien von Salamandra maculosa,” pp. 143-4. Arch. f. mik. 
Anat., Bd. 44, Hft. 1, 1894. Through the courtesy of Dr. Watasé, I have been able 
to apply Korschelt’s method to the sperm cells of Szve, and I find that these con- 
tain a granular substance similar to the archoplasm of AJlolobophora foetida. 
Many of them resemble very closely my Fig. 1 (a young odcyte). These results 
recall Nussbaum’s identification of the Vesenxkern of a variety of gland cells with 
the Dotterkern of eggs and the (Vebenkern of the spermatocytes: “ Dagegen wird 
man den Nebenkern der Driisenzellen wohl mit dem von Wittich entdeckten 
Dotterkern der Eier, dem durch von la Valette St. George zuerst bekannt gewor- 
denen Nebenkern der Spermatocyten, den von Leydig aus der Epidermis von 
Pelobates-Larven beschriebenen Bildungen in eine Categorie bringen diirfen.” 
Moritz Nussbaum, “ Ueber den Bau und die Thatigkeit der Driisen.” Arch. f. 
mtk. Anat., Bd. 21, 1882, pp. 343-4. Later, Balbiani says: “Le noyau vitellin 
(Dotterkern) des Araneides est homologue du Nebenkern (centrosome de 
Platner) des cellules seminales et du centrosome des cellules somatiques.” E. G. 
Balbiani, “ Centrosome et Dotterkern.” Journ. de 1’Anat. et dela Physiol., tome 
XXIX, 1893. 
