50 PHARMACEUTICAL BOTANY 
2. MerapHase.—Arrangement of the double chromosomes: 
at the equatorial plate with their daughter halves drawn apart in 
V-shaped fashion. Attachment of spindle fibers from poles of 
spindle to the halves of the chromosomes. 
3. ANAPHASE.—Separation of the daughter halves of each 
double chromosome. Movement of one-half of each double 
chromosome to each of the poles of the spindle. Formation of 
two dense knots or masses of daughter chromosomes, one at each 
pole. 
4. TELOPHASE.—Expansion of the masses of daughter chro- 
mosomes at the poles, and their division into linin-carrying 
chromatin granules, and the complete organization of the daugh- 
ter nuclei. Appearance of a nuclear membrane around each ~ 
daughter nucleus. Appearance of a nucleolus or of nucleoli in 
each daughter nucleus. Construction of a cell plate between 
the two daughter cells. Splitting of the cell plate to form plasma 
membranes. Formation of the middle lamella between the 
plasma membranes. Formation of a cell wall by each plasma 
membrane. 
NuMBER OF CHROMOSOMES.—The number of chromosomes 
found in the cell nucleus varies with the kind of cells considered 
in each individual and with the species. Every species of plant 
or animal has a definite number of chromosomes that appear 
when its body cells undergo mitosis. In all sexually-reproducing 
plants or animals two kinds of cells occur, the body- or somatic- 
cells and the germ cells. Each of the body cells contains twice as 
many chromosomes as each of the germ cells. Thus, the Stra- 
monium contains 24 chromosomes in each of its body cells and 
12 in each egg and sperm cell. The number of chromosomes in 
the body cells is constant, is called the diploid or species number, 
and is expressed as 2x. The number in the germ cells is called 
the haploid number and is expressed as x. 
MEIosis oR MATURATION 
The process whereby the diploid number becomes haploid is 
called meiosis or maturation. 
Each of the spore mother cells which give rise to pollen grains 
and to eggs in plants are formed by the division of body cells and 
