230 ; The Significance of Sex. [March 
gonidium) with which to fuse. As the chance of cross-fertiliza- 
tion is greater in proportion to the number of these microgonidia, 
they have acquired the habit of dividing a few times after their 
separation from the macrogonidium before starting out on their 
search for partners. Here, as with Arion, a small quantity only 
of the idioplasm is needed to effect fertilization. We do not 
contend that there may not be some advantage in starting with 
a large quantity of idioplasm, but we do call attention to the. fact 
that, compared with the vigor due to the mixture of idioplasms 
of diverse experience, such advantage becomes quite secondary. 
We may now pass to the consideration of the phenomena of 
copulation. The simplest cases join easily on to the case last . 
considered. When the bud from the nucleus is not carried away 
y cell-division it may still be transferred to the interior of 
another cell, if. such cell be brought with an aperture close to a 
corresponding aperture of its own cell. When the nuclear bud 
is produced at the time of the fertilization, Engelmann terms the 
metz “ periodic hermaphrodites” (so far as this implies sex it is 
a misleading term). When, however, the nuclear bud remains as 
a permanent endoplastule and does not conjugate with the endo- 
plast, except perhaps for a brief period in connection with fertili- 
zation, after which it is immediately budded off again to form the 
endoplastule, then Engelmann calls such a cell a “ permanent 
hermaphrodite.” In some cases the whole reproductive function 
may have passed over to the endoplastule, so that this never con- 
jugates with the endoplast, but rather by its own division builds 
up the latter when this disintegrates. Periodic hermaphrodites 
are Stentor, Spirostoma, and Trachelius; while permanent her- 
maphrodites are Stylonychia, Euplotes, and Paramcecium. 
ulation is most frequent with the Ciliata, but has been ob- 
served in Peridinium and in one-chambered Rhizopods. An al- 
ternation of copulation with conjugation occurs in Stylonychia 
and in Platoum (Troglodytes). See Gabriel. 
~ In connection with conjugation and copulation there is in all 
the higher forms a segmentation of the nucleus, or of the endo- 
plast and endoplastule respectively. The last leads in the di- 
vision, car stiri engi era Sri eng eh _The 
