240 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
the peripheral cells. Such an explanation, if not so fundamental, 
certainly has the advantage of being more in harmony with the 
facts known at the present time. 
The chief objection to Stevens’s interpretation of the cause of 
nuclear migration is based upon more fundamental grounds. It 
calls into question the validity of the general application of the 
theory itself. Early in the development of the oosphere of Araio- 
spora, there is a distinct accumulation of fine meshed cytoplasm at 
its center. This cytoplasm, it will be recalled, is finely alveolar, 
stains more deeply with gentian and retains its general form until 
after the sperm is introduced. The only other portion of the 
oosphere that consists of fine meshed cytoplasm is the receptive 
papilla. Soon after the sperm is admitted, the central mass begins 
a radial migration and can be traced from center to circumference. 
When all but a small portion has left the center and there is an 
abundance of fine meshed cytoplasm at the periphery, the oospore 
begins laying down a cell wall. In other words this fine meshed 
cytoplasm acts precisely as if it were kinoplasm. It accumulates at 
the center of the egg and in the receptive papilla when these parts 
are the centers of activity. After the sperm nucleus is introduced, 
the central region largely disappears and fine meshed cytoplasm is 
abundant at the periphery where again cytoplasmic activity is great¬ 
est. If the above interpretation that the whole central portion of 
the oosphere is kinoplasm, or active cytoplasm, be correct, it stands 
in direct opposition to Strasburger’s view that the egg is poor in 
kinoplasm until after the sperm is introduced. In this connection 
Wilson’s (:01) researches on artificially fertilized eggs of Toxo- 
pneustes are of interest. Wilson took the utmost care to eliminate 
all chances of normal fertilization and proved conclusivelv both by 
control experiments and by cytological evidence that no sperm nuclei 
were present. These artificially fertilized eggs into which no kino¬ 
plasm could have been introduced from the male organs, had, in 
many cases, a great portion of their interior filled with asters, cen- 
trosomes, etc., developed from the ooplasm in response to a “non- 
localized stimulus.” These “ cytasters ” and “ cyto-centrosomes n 
were also produced in artificially fertilized, enucleated, ooplasmic 
fragments. To the writer the foregoing facts are difficult of inter¬ 
pretation in the Jiglit of any theory that assumes an absence of 
kinoplasm or active cytoplasm in the egg previous to the introduc¬ 
tion of the sperm nucleus. 
