No. I.] YOLK-NUCLEUS AND POLAR RINGS. 9 
Fig. 9 represents a longitudinal section through one of the 
fertilization cones, that part of the sperm which is still within 
the cone being indicated. In this figure we again see the ten- 
dency of the archoplasm to accumulate at the centres of activity ; 
it is collected around the entering sperm. The extent of the 
cone 1s dependent upon the length of sperm within the egg, and 
the aggregation of the archoplasm (especially after fixatives that 
destroy radial structure) seems to be the sole factor that gives 
form to the cone. In applying the same method of staining 
to the spermatozoén at various stages of its development, I 
have not been able to obtain any reaction indicating the pres- 
ence of archoplasm ; hence it appears that this relatively large 
mass of archoplasm of the cone has not been brought into the 
egg by the sperm. The question is here suggested : Is not 
the archoplasm of the cone identical with the sperm archo- 
plasm of other eggs? Boveri! says: “Auf diesem Stadium 
nun finden wir das Archoplasm als einen dichten kugeligen 
Hof um das im Centrum des Eies gelegene Spermatozoon 
(Fie, ro-und; 11, Taf. 1; Fig. 26, Taf. Il): Es) stellt: sich’ an 
den beweisenden Praparaten als eine betrachtliche Ansamm- 
lung einer gleichmassig kornigen Substanze dar, die nach 
aussen ziemlich scharf abgegrenzt ist, wahrend die iibrige 
Zellsubstanz vollkommen homogen erscheint”’ (p. 65). 
Fig. 10. As soon as the first polar body is constricted off 
we no longer find a fertilization cone; but we find a sperm 
attraction-sphere with d/ue archoplasm at the point previously 
occupied by the blue archoplasm at the apex of *the cone. 
At this stage (Fig. 10) the sperm head is contracted into a 
relatively short, thick rod, with its attraction-sphere occupying 
a position nearer the attraction-sphere of the lower pole of the 
spindle than does the rod itself. The structure of the sperm 
attraction-sphere is identical with that of the egg attraction- 
sphere described above (Fig. 7). This figure (Fig. 10) suggests 
that the archoplasm of both sperm and egg attraction-spheres 
is furnished by the egg alone. In the case of the sperm 
attraction-sphere we have evidence only that the middle-piece 
1 Th. Boveri, ‘‘Zellen-Studien.”’ Hft. 2, Jena, 1888. 
