398 THE AMERICAN NATURALIST. [VoL. XXXIV. 
That these are really cleavage, and not merely amceboid phe- 
nomena, can hardly be matter of serious doubt, even when con- 
sidered from the more superficial phenomena already presented. 
If, however, other evidence were needed, it is available in the 
greatest profusion from sectional sources, portraying the inter- 
nal structure and organization of the egg. In Pl. IV, Figs. 
1-6, are shown camera sketches, of a few sections only, of 
eggs in different stages of segmentation. That they are clearly 
correlated in general features with the superficial features 
already noted there is no doubt whatsoever, though there may 
be many points of detail which need attention, but which can 
only be touched upon at this time. That Pl. IV, Fig. 2, is com- 
parable with that of Pl. II, Fig. 7, as a two-cell stage must be 
obvious at a glance. There are, however, here some interest- 
ing facts to which a moment's consideration may be directed. 
It will be seen, for example, that there are present, in the sec- 
tion, portions of several nuclear figures, a somewhat unusual 
condition at this stage of development. However, here again 
there is something in common with what Wilson has recorded 
in certain cases in Renilla, namely, the internal nuclear divi- 
sion preceding that of the cytoplasm which followed, or lagged, 
as it were, finally dividing at once into an equal number of cells. 
It is, however, quite different in that in these the nuclear cleav- 
age seems constantly to outrun that of the cytoplasm. It had 
occurred to me that possibly there might be here what has 
been noted by Loeb (99), Norman (96), and others, namely, a 
sort of artificially produced cleavage of the nucleus, induced by 
some chemical or pathological stimulus. The comparison of 
many sections, preserved under different conditions, and by 
different methods, however, leads me to conclude that it is a 
perfectly normal condition so far as these particular eggs are 
concerned. I have also observed the same thing in the eggs 
of other hydroids, and Hickson (93) calls attention to a similar 
condition in the cleavage of Allopora. It would seem as if 
from some cause, not perhaps easily distinguishable, that all 
the phenomena of cleavage in some of these organisms have 
been greatly modified, that in some way the nucleus and cyto- 
plasm have, as it were, been thrown out of concord, and their 
