Heredity and its Bearings on Atavism. 137 
nucleolar matter, as the latter, especially in the ovum, gives 
rise to a number of paranucleoli or accessory nucleoli, which 
gradually lose their chromatin, leave the nucleus by passing 
through the nuclear membrane, and then become ultimately 
absorbed. Again, the remarkable fact of the nucleolar 
membrane of the “male” nucleolus being shed, reminds us 
of the fate of the four “male” chlorophyll-bands in the 
zygote of Spirogyra nitida. 
How great the activity of endonucleoli is, may also be 
gathered from my paper, but now I must restrict myself by 
returning to a consideration of how the “ male” and “ female ” 
demi-nuclei behave during fecundation. I stated above 
(p. 134) that there may be either a union of the two demi- 
nuclei to form a resting nucleus (“zygote” nucleus or 
Furchungskern), or that the nuclear contents may take part 
directly in the formation of the nuclear spindle (Furchwngs- 
spindel). In the latter case the attractive spheres exert 
their influence at once, while in the former case the zygote 
remains dormant for a time, in some instances probably 
because of want of nourishment, eg., the primary endosperm 
nucleus of Angiosperms remains quiescent till an extra 
supply of nourishment is conveyed to the ovule as the result 
of the irritation set up by the fecundation of the ovum. 
At any rate, I should conclude theoretically that the zygote 
cannot undergo division till an equilibrium between the maternal 
and the paternal “cell organs” has been established; and this 
balance I stated in my last paper to be brought about thus : 
the starving cell organs of the male cell feed on the 
surplus nourishment stored up in the female cell, and in 
consequence they increase in size till they are quite as large 
as the female organs, an observation readily demonstrated in 
the Embryo-sac of Angiosperms, in which the small spindle- 
shaped male nucleus derived from the pollen-tube ultimately 
becomes of the same size as the large globular female nucleus. 
During this stage of fecundation, then, the male cell must 
be looked upon as truly parasitic in its habit, and it is 
this very parasitism which reduces the available amount of 
nourishment in the ovum, and which calls forth the activities 
of the female cell organs. ‘The latter find themselves passing 
