42 MARCUS M. HARTOG. 
of further vital evolution. In Dallinger and Drysdale’s group 
the whole zygote is resolved into uninucleated spores; and 
the process in Noctiluca is a mere modification of the 
same process. 
2. Rhizopoda and Heliozoa. 
Conjugation is known to occur in some members of this 
group ; the gametes appear to be ordinary individuals ; but we 
have no full knowledge either of the antecedent or consequent 
processes. 
3. Gregarinida. 
The details of conjugation in this group are not fully made 
out, but that of OpHryocystis isinteresting. In this genus the 
apocytial body is first resolved into uninucleate cells, which con- 
jugate. The two nuclei are stated not to fuse, but to give 
rise to six, two of which unite to give rise to a zygote-nucleus, 
around which the cytoplasm aggregates, while the other four 
nuclei pass to the peripheral cytoplasm, which degenerates 
with them. Obviously the conjugating cells are progametes, 
which only develop gametonuclei afterwards; and of these 
last, two only are functional: the peripheral cytoplasm 
and the other four nuclei represent arrested gametes. It 
would be interesting to know if the tripartite division of 
the nucleus of each of the conjugating animals corresponds to 
the schema annexed (Fig. 5), where Nn, M, represent the 
M! 
x 1 
x{ |. 
Sires [2 | —M? 
N} 
Fic. 5.—Tentative schema to explain the conjugation of Ophryocystis. 
N, M, are the primitive nuclei of the conjugating pair ; successive stages 
are separated by dotted lines, and the rejection-nuclei are surmounted by 
dashes; the square encloses the zygote-nucleus Z, formed by the union 
of N?, M*. 
