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THE ORGANIC CELL 
substance by which the various hereditary factors are passed 
on from generation to generation. 
With regard to the structure of the nucleus it must be noted 
that the nucleus itself passes through two different states, each 
of which presents a very different appearance. 
In the first or vegetative phase, falsely known as the ‘ resting 
state/ the following elements may be made out : — 
1. The nuclear membrane — well defined and clearly 
differentiating the nucleus from the surrounding cytoplasm. 
2. The nuclear reticulum — an irregular branching network 
which is made up of two essentially different substances : 
(a) The protoplasmic basis of the nucleus called linin visible 
after staining, and closely allied to the cytoplasm of the cell- 
body ; ( b ) The deeply staining substance called chromatin, 
the most important factor in the cell, which is often the only 
substance of the nucleus that is passed on during the process 
of division from cell to cell, and which is capable of producing 
all the other elements. The chromatin may be present in the 
form of granules of different sizes, these granules being embedded 
in the linin. The chromatin often appears as a network closely 
intermingled with the linin network. As we have seen before, 
it consists largely of nuclein, which in its turn is a compound 
of nucleinic acid with albumins. It shows a great affinity for 
the basic-tar colours, and the depth of the staining capacity 
at any given period is an index of the proportion of nucleinic 
acid present. 
B. The nucleoli, one or more bodies found in the nuclear 
network, which however may be absent. The nucleoli are 
of two different kinds — the plasmosomes, which are different 
in composition from chromatin, as shown by the action of 
stains ; and the net- knots or karyosomes, which are closely 
allied to chromatin, if not identical in composition. These 
latter nucleoli are doubtless condensed portions of the regular 
chromatin network. 
4. The ground-substance, or karyolymfh, fills the spaces 
of the network, and is very negative in its staining activities. 
It is interesting to note that the chromatin network shows 
a great degree of variation in its arrangements, and may exhibit 
the extremes, either of a loose reticulum as in the various 
