472 
Sargant . — The Formation of the 
a series of karyokinetic divisions has been much debated,, 
My observations do not exclude the possibility of such 
identity. If the network of the resting nucleus be con- 
structed of a single much convoluted filament, and if this 
filament possess all the properties characteristic of a chro- 
mosome, then the chromosomes may preserve their identity 
throughout a resting-period. We must consider the substance 
called amorphous chromatin to be of the nature of a food- 
stuff. I am more disposed to think that the chromosomes 
are re-cast during each resting-period, part of their chromatin 
appearing in the amorphous form for redistribution on the 
spirem ribbon. With regard to the allied question of the 
relation between dotted ribbons such as those of the im- 
mature chromosome in Fig. 19 a, and the homogeneous 
ribbons of a later stage, there is little to say. The change 
takes place suddenly, and no differentiation can be observed 
in the ribbon afterwards. A dark line can indeed be traced 
along its edge, but this is probably due to double refraction. 
There is no evidence to indicate that the identity of the dots 
is preserved, but it is not impossible that an incomplete 
fission may correspond to the plane which separated the two 
rows of dots. 
In describing the phenomena of synapsis I have traced 
a connexion between the nucleolus and the linin both of the 
spirem ribbon and of the immature chromosomes. Drops of 
nucleolar matter are frequent in the cytoplasm during the 
early stages of spindle formation, and Mr. J. E. S. Moore 
once pointed out to me in a preparation from the second 
embryo-sac karyokinesis that a number of these small drops 
or granules were applied to each chromosome in the nuclear 
plate. I have frequently observed the same thing since in 
other preparations of that stage. It would certainly suggest 
that the nucleolus plays some part in the growth of the 
chromosomes. The history of their formation from the first 
embryo-sac nucleus shows that they must contain a great 
deal of linin. 
Little has hitherto been said of the achromatic structure of 
