VEGETABLE CYTOLOGY 
43 
their nuclei come together and their protoplasm blends to form a 
new cell. This is the common method seen in higher plants. 
Conjugation. — A union of two gametes, alike in character, the 
product being a zygote or zygospore. This method of reproduction is 
seen in the molds, Spirogyra, Zygnema and Diatoms. 
Fertilization. — A union of two unlike gametes or their nuclei, the 
product being an oospore. One gamete, the male sexual cell, is 
smaller and active while the other, the female sexual cell is larger 
and passive. This process is seen among the higher and many of 
the lower plants.' 
INDIRECT NUCLEAR DIVISION (MITOSIS OR KARYOKINESIS) 
This is the general method of division seen in the formation of 
tissues of higher plants. 
The process begins in the nucleus and ends with the formation of 
a cell wall dividing the new-formed cells. 
When we examine a cell in its resting stage we find the nucleus 
more or less spherical in shape, surrounded by a nuclear membrane 
and containing a nuclear network, nuclear sap and one or more 
nucleoli. The nuclear network consists of a colorless network of 
linin adhering to which are numerous minute granules called chro- 
matin which take the stain of a basic dye. Surrounding the nucleus 
is the cytoplasm. 
As the cell commences to divide, the nucleus elongates and the 
linin threads of the nuclear reticulum shorten, drawing the chro- 
matin granules together into a thickened twisted chromatic thread. 
This thread splits transversely and thus becomes divided into a 
number of rods termed chromosomes. Each of these then splits into 
two longitudinal halves that may be termed the daughter-chromo- 
somes. They lie within the nuclear cavity united by delicate threads. 
There now begins a phenomenon concerned with the cytoplasm 
which is primarily a process of spindle formation. The granular 
cytoplasm accumulates at the poles of the elongated nucleus forming 
the cytoplasmic caps. Presently it begins to show a fibrillar struc- 
ture, the threads extending outward around the periphery of the 
nucleus forming an umbrella-like arrangement of fibers from both 
