SOME PROBLEMS OF REPRODUCTION. 7 
isogamy. By endogamy I imply the union of gametes from a 
single gametogonium, by exogamy their union with those 
from other oogonia exclusively. Portions of the nucleated 
or non-nucleated protoplasm, left out in schemes of gametal 
formation, are termed epiplasm. I have found it useful to 
introduce the following notation to denote relationship among 
nuclei, viz. to use a given letter for the parent nucleus, and the 
same letter with that figure as an index which denotes the 
number of bipartitions that have taken place, to denote a 
brood-cell issuing from those bipartitions; thus if N be a 
nucleus, N*® will denote a brood nucleus of the 5th bipartition 
of N; the notation is abbreviated, N* denoting N+2*. 
II. Typicatty AGAmic REPRODUCTION. 
Before examining into gametogeny we must note the exist- 
ence of a group of organisms which appear to be essentially 
agamous. I refer to that of Mycrtozoa, including the 
Monadinee of Cienkowsky, the Acrasiex, and the Myxo- 
mycetes proper. 
In the Monapinea, a group relegated with exceptional 
liberality by the zoologists to the botanical “sphere of in- 
fluence,” we have a very primitive group, most species having 
the three forms of Mastigopod, Myxopod, and Cyst, beside a 
Resting Stage, which is never preceded by karyogamy. The 
adult forms may become plurinuclear or fuse into plasmodia 
like the Myxomycetes, but no nuclear union takes place; 
nay, even in the plasmodia further nuclear divisions may 
occur. 
In the true Myxomycetss, plasmodial fusion always precedes 
spore formation. Possibly, as has often been suggested, plas- 
modial formation has led to the various modes of karyogamy. 
The nuclei pass freely from place to place in the plasmodium, 
and may eventually be far removed from what was their ori- 
ginal cytoplast ; and the cytoplastic elements again undergo a 
reorganisation by their fusion, which we may term plasto- 
gamy. In this way is fulfilled what I regard as the object 
