the Nucleolus in Heredity. 
275 
is neither an absolute nor a relative increase of nucleolar 
matter accompanying the specialization of the cell. Nor is 
this contrary to what might be anticipated. For it is very 
probable that only a few of each kind of inactive idioblast 
would be present in the nucleus, while those which are active, 
or about to spring into activity, would be multiplied. This 
uneven multiplication would of course lead to an apparent 
reduction in number of latent idioblasts and an increase in 
number of active hereditary units. There is a second source 
of inaccuracy which may at present enter into any endeavour 
to estimate the number of idioblasts from the amount of 
hereditary substance, and which should not be lost sight of. 
Whether we regard the chromatin alone, or the chromatin and 
the nucleoli as the bearers of the hereditary properties, in all 
probability there is much extraneous matter present besides 
the actual vehicle of the properties of inheritance in this 
so-called hereditary substance, and varying conditions may 
lead to varying amounts of this extraneous matter being 
present. As bearing out this statement it may be mentioned 
that it has been shown by Liebermann, Altmann, Malfatti, 
and Kossel, that the percentage of albumin in the chromatin 
of nuclei is very various 1 . 
Another nuclear phenomenon, which has been brought into 
prominence recently by numerous observers, is rendered, 
I think, more intelligible by the proposed view of the 
properties of the nucleoli and chromatin. I refer to the great 
attenuation and elongation of the nuclear thread during the 
‘ Dolichonema ’ stage (Rosen ) 2 which immediately precedes 
synapsis in the formation of the reproductive cells. 
During this stage the nuclear (chromatin) thread becomes 
enormously long and thin ; while the nucleoli fuse together 
into one, which then becomes reduced in size. At the 
beginning of synapsis the nucleolus is much reduced, and in 
fixed specimens there appears a ‘ sickle ’-shaped (rather 
concavo-convex) body in contact with the inner surface of the 
1 Wilson, 1 . c., p. 241. 
2 F. Rosen, Beitrage zur Kennt. d. Pflanzenzellen ; Cohn’s Beitrage, vii. 2, 1895. 
