THE LIVING CELL 41 
(0) Tue Nucteus, a denser, definitely circumscribed region 
of protoplasm containing nucleoplasm which consists of gels of 
varying consistency containing chromatin, a substance staining 
heavily with certain basic dyes, adhering in the form of granules 
to a network of dimin. NucLear Sap, consisting of a watery 
solution of nourishing substance is also found in the nucleus. 
The nucleus may be regarded as the superintendent of the cell 
Saad ain, ee 
ry i Pia rattle 
= 2 
o 6 ec: 8 6 
Fic. 22.—Diagram of Plant Cells: a, cell wall; 4, cytoplasm; ¢, cytoplasmic 
strand; d, nucleus; e, plastid; /, plasmodesma, passing through pit in cell wall; g, 
sapvacuole. (Drawing by H. McCarthy, from Stanford’s “‘Economic Plants,” D. Appleton- 
Century Co. Publishers.) 
since it controls the structural changes and physiological activi- 
ties that take place within the living cell. It is usually spherical 
in shape but in some plant cells is ovate, ellipsoidal, stellate, 
discoidal or elongated. The chromatin is the substance which 
carries those characters or factors from parent to offspring which 
determine that the offspring shall resemble its parent or parents 
and past ancestors. 
(c) Tur Nucieo.us, a small body of dense protoplasm within 
the nucleus. Sometimes two or more nucleoli may occur within 
a nucleus. The nucleoli are believed to represent reserve food 
which is employed in the metabolic processes of the nucleus. 
Od 
ae: 
