202 MEAD. [Vor. XIV. 
each centrosome, and the rays of the aster —which have never 
been absent — diverge from it, rather than directly from the 
centrosome. The centrosome at the inner end of the spindle 
often, perhaps always, divides, but the daughter-centrosomes 
are not so large as the corresponding ones in the first spindle, 
and always remain close together (Figs. 28, 29). 
The chromosomes, during the metaphase of the second matu- 
ration-amphiaster, are frequently dumb-bell shaped (Figs. 26, 
27), and sometimes in four parts, as shown in Fig. 28. The 
succeeding phases are similar to those of the first maturation- ° 
amphiaster described above. The peculiar “wake” left in the 
midst of the fibres of the central spindle by the receding halves 
of the chromosomes is evident during the anaphase, and by 
this means one can ascertain which of the daughter-chromo- 
somes were together (Fig. 29). It is found in some instances 
that one of the chromosomes is drawn much nearer the pole of 
the spindle than its counterpart.} 
The second polar globule is formed directly under the first, 
which is thus pushed away (Figs. 31-33), and it contains the 
centrosomes and the nine daughter-chromosomes (Fig. 31). 
At about the 32-cell stage, both polar globules are ingested 
by the apical cells.2 The Zw¢schenkorper, which is developed 
during this mitosis, persists for a considerable time, as may be 
seen by comparing Figs. 31, 32, 35, 37, and 39. 
As the spindle vanishes the chromosomes which were at the 
inner end elongate and bend so as to become V-shaped (Figs. 
31-33). They then group themselves in a hollow hemisphere 
whose concave side is directed toward the centre of the egg so 
as partially to obscure the centrosome and its vaguely defined 
centrosphere, though at this period the radiations from the aster 
in question are extensive and very distinct, many of them cross- 
ing those of the male aster. The chromosomes ultimately 
surround the centrosome so that the astral rays diverge from 
their very midst (Figs. 33-35). 
Gradually the chromosomes become vesiculated and, as the 
nine vesicles begin to migrate toward the male pronucleus, they 
1JIn this figure the lithographer has slightly displaced the outer centrosomes 
and the chromosome nearest the pole. 2 Cf. Mead, '97b. 
