1887] : The Significance of Sex. 227 
fertilized eggs. But this phenomenon has not received the at- 
tention it deserves. 
In polyspermy we find that not only does the female nucleus 
form an amphiaster, either alone or by zygosis, with one male 
nucleus, but that the male nuclei left unconjugated also form 
amphiasters. This phenomenon was first studied by Fol, 1879, 
but Hertwig has just published an article fully illustrating these 
forms. If more than one spermatozoon conjugates with the 
female nucleus it develops a tetraster (sometimes a triaster), or 
a figure having a greater number of poles according to the num- 
ber of spermatozoa fusing. It results that segmentation follows 
a series whose terms are multiples of the normal one. But this 
only when there are no free spermatozoa in the yelk, for in such 
a case each of these also segments and receives its bud of cyto- 
plasm, thus making the segmentation of the egg irregular. 
When the nuclei fuse before the spindle is formed, the number 
of spindles seems to depend on the number of nuclei. (This 
may be doubtful, as the poles seem to be determined by asters 
independently arising in the yelk, which migrate to the nuclei and 
direct their transformation.) But the amphiasters and the more 
complex tetrasters, etc., may also unite among themselves, re- 
gardless of sex, by superposition of poles, thus building up 
complex figures that may be as regular as a dodecahedron. 
The result is the fusion of daughter-nuclei of diverse origins. 
It follows, therefore, that the spermatic nuclei after one segmentation 
have an affinity for each other. Hertwig found further, that the 
nuclei resulting from the segmentation of pronuclei became fused 
again, but whether there was subsequent division and normal 
development remains an obscure question. The male nuclei also 
form triasters and tetrasters which cannot be distinguished from 
those made by the female pronucleus; but it is possible that in 
these cases multifecundation has taken place. Besides Fol and 
Hertwig, polyspermy has been studied by Bergh and Horst, 1881, 
and by Strasburger in phanerogams; Salenka and Schneider 
report normal development as following polyspermy ; but this 
subject also requires further study. 
Another line of study has been followed by Hertwig. It is 
well known that certain nuclei which are not too closely nor too 
distantly related to each other are prepotent in zygosis above 
ag a = am mn afi foi 
VOL. XXI.—NO. 3. 
