SOME PROBLEMS OF REPRODUCTION. 43 
nuclei of the conjugating cells. In this case the rejection- 
nuclei would be of different generations, like the first and 
second polar bodies. 
In Monocystis Wolters has shown! that the nucleus of 
either conjugating individual divides into two, a rejection- 
nucleus which passes out like a polar body, and a gameto- 
nucleus which fuses with that of the other individual, 
4, Radiolaria. 
In Coxttozoum and SrH#Rozoum anisozoospores (of two 
sizes) are formed, but are not known to conjugate. The size 
of the anisozoospores is inversely proportioned to the number 
of the brood. Both are formed by preliminary divisions of 
the nucleus, and the resolution of the contents of the central 
capsule into uninucleate swarmers. 
5. Crliata, 
a. Free Ciliata and Suctoria. 
The conjugation in this group differs from that in any other, 
for in either gamete two pronuclei are formed, one of which is 
exchanged for a pronucleus derived from the other gamete; 
in each gamete the original and derived pronuclei fuse to form 
a new nucleus; and the two separate without cytoplasmic 
fusion, and after a time resume their normal life and fissiparous 
powers. To understand fully this process we must premise 
that the nuclear apparatus of the Ciliata is double, consisting 
of a larger and smaller element, now termed meganucleus 
and micronucleus respectively. The meganucleus divides by 
mere constriction, the micronucleus by a true mitosis, in fission ; 
and there is reason to believe that the meganucleus is the seat 
of what we may term the physiological properties, the micro- 
nucleus of the morphological or atavistic properties of the 
single nucleus of other organisms. A fact that supports this 
1 In ‘Arch, f. mikr, Anat.,’ vol. xxxvii, 1891, p. 91. 
