47 ° Sargant . — The Formation of the 
1. The resting-stage is the same in both. The young 
resting nucleus of the embryo-sac cannot be distinguished 
from the nucellar nuclei which surround it. Later on it 
surpasses them in size, but in structure is essentially the 
same. 
2 . The condition of synapsis is peculiar to the primary 
embryo-sac nucleus, and to that of the pollen mother-cell. 
Its characteristic features are contraction of the chromatic 
thread to one side of the nuclear cavity, partial solution of 
the nucleolus, and partial disappearance of the nuclear mem- 
brane. I have never met with a similar contraction either in 
vegetative nuclei or in those produced by embryo-sac divisions. 
Partial solution of the nucleolus may sometimes be observed 
in the four nuclei of the embryo-sac about the stage of 
Fig. 34. Possibly this may be an indication of approaching 
division. It should be observed however that the contraction, 
which is by far the most striking feature of synapsis, may 
perhaps be of little importance compared to the other char- 
acters. If, for example, it were merely a device to prevent 
the half-dissolved nucleolar matter from escaping into the 
cytoplasm, it would be useless in a smaller nucleus, for the 
meshes of the chromatic thread would be fine enough to serve 
this purpose without contraction. Partial solution of the 
nucleolus together with a vaguely outlined membrane are 
characters which in such a nucleus would readily escape 
observation. 
3. The structure of the spirem stage in the embryo-sac 
nucleus is very different from that of the vegetative spirem. 
Perhaps they should be distinguished by different names. 
They both possess a coiled chromatic ribbon and nucleoli 
within the nuclear membrane. The ribbon of the vegetative 
spirem however stains uniformly like chromatin, while the 
spirem ribbon of the primary embryo-sac nucleus is erythro- 
philous, and bordered on either margin by chromatin granules. 
I have searched in vain among vegetative nuclei for a slender 
spirem in which a similar differentiation may be observed. 
It is very possible however that such a stage may exist while 
