232 The Significance of Sex. [March 
extruded, due to fertilization, and a new nucleus arises endoge- 
nously, and this is rejuvenescence. In 1882, Balbiani showed that 
there was an interchange of nucleoli; and Jickeli, in 1884, saw 
two nucleoli in the act of passing each other across the line 
separating the gametes. Lankester could find no interchange, 
but said that a portion of the segments of both bodies are lost, 
the remaining ones fuse to constitute the new nucleus and nucle- 
olus, but with reversed functions. (See Fig. 128.) 
' Maupas, in 1886, said all the products of the nucleolus are 
lost except one; this divides, and one daughter remains and one 
crosses to the other gamete to fuse with the stay-at-home over 
there. The resulting zygotes segment to eight daughters; of 
these, three are absorbed, four become nuclei, and the eighth, after 
repeated divisions accompanying cell-division, becomes four 
nucleoli. The old nucleus is absorbed. Plate, in the same year, 
saw no interchange, but did see two nucleoli in apposition with a 
wall between. Gruber, however, saw the same thing, but no wall 
between, so that there was a chance for some interchange of sub- 
stance. There was no fusion, however, for the nucleo-gametes 
separated and returned to divide into four. Gruber thinks the 
“ stay-at-home” nucleolus acted in a similar way, for eight nucleoli 
result, and four of these fuse to form a new nucleus, the other 
four fuse to make a new nucleolus. 
Truly, when such eminent observers disagree, who can decide ? 
For our present purposes it is sufficient to know that there is an 
interchange in this case as in all others of fertilizing material, 
and that this is mutual and reciprocal. We cannot here, as did 
the older observers, speak of male and female idioplasm. That 
the functions of the endoplast are different from those of the 
endoplastule is evident, but Weismann’claims that the reproduc- 
tive plasma is restricted to the latter, while the former has only 
histogenic plasm. Thus, from a survey of fertilization in its rela- 
tion to the nuclear phenomena, have we been enabled to get 
pretty clear notions of the significance of sex. But our morpho- 
logical inquiry would not be complete did we not study the 
various methods of cell reproduction and observe the relations 
of these to the Tena of gaet Several of the lows 
