CHAPTER I. 
THE MORPHOLOGY OF BACTERIA. 
Bacteria Defined. 
A. Morphology — Normal Forms: Coc- 
cus, Bacillus, Spirillum. 
B. Morphology— Atypical and Abnor- 
mal Forms. 
1. Variation. 
2. Degeneration and Involution. 
3. Pleomorphism. 
4. Branching. 
C. Size of Bacteria: Weight of Bac- 
teria. 
D. Structure and Constituents of the 
Bacterial Cell. 
1. Cell Membrane, Ectoplasm, Cap- 
sule, Zooglea. 
2. Cell Substance, Cytoplasm, Nu- 
cleus, Metachromatic and Polar 
Granules, Flagella, Spores, Ger- 
mination of Spores, Arthro- 
spores. 
E. Reproduction and Cell Division in 
Bacteria. 
F. Cell Grouping. 
G. Cla.ssification of Bacteria. 
1. Relation of Bacteria to Higher 
Plants. 
2. Classification. 
H. Mutation. Constancy of Types. 
Bacteria are rigid, unicellular organisms, devoid of chlorophyll or 
other photodynamic pigment; they possess no morphologically dem- 
onstrable nucleus, although they contain nuclear material, and they 
reproduce by simple transverse fission, the resulting individuals being 
of approximately equal size. 
A. NORMAL FORMS : COCCI, BACILLI, SPIRILLA. 
The normal forms of the true bacteria are very simple, and are 
included in three fundamental types: the sphere (coccus, plural cocci), 
the straight rod (bacillus, plural bacilli), and the curved rod (spirillum, 
plural spirilla). There is in addition a group of organisms intermediate 
between the true bacteria and the molds, which is characterized by a 
filamentous type of growth. The members comprising this group of 
filamentous organisms are commonly known as the higher bacteria 
or Chlamydobacteriacefe. Of these higher bacteria, some of the 
Streptothrix and Actinomyces types are formidable invaders of man. 
An organism belonging to one of these groups always reproduces its 
kind under normal conditions; that is, a coccus always reproduces a 
coccus, a bacillus always reproduces a bacillus, and a spirillum always 
reproduces a spirillum. 
Cocci.— A single coccus is typically spherical, although those organ- 
isms in which division is taking place may be temporarily somewhat 
elongated in one diameter, thus appearing oval in outline at this stage 
of their development. They may even resemble very short bacilli in 
extreme instances. The habitual occurrence of cocci in pairs, fre- 
quently with their proximate surfaces flattened, is a noteworthy mor- 
