VEGETABLE KINGDOM. | +---------------+--------+-------+------------------+ | | | | Thallophyta. Muscineæ. Pteridophyta. Phanerogamia. [= The lowest forms of vegetable life. No differentiation into root, stem, or leaf.] | Protophyta. [= No sexual reproduction.] | +-------+------------+ | | Algæ. Fungi. [= Chlorophyll [= No chlorophyll.] present.] | | +--+--+--+--+--+--+ | | | | | | | | Schizomycetes {(1) Coccaceæ[4]--round cells. [= multiplication by cell { division or by spores] {(2) Bacteriaceæ--rods and threads. { or {(3) Leptotricheæ. } Bacteria. { } Higher Bacteria. {(4) Cladotricheæ. } _Structure and Form._ Having now located micro-organisms in the economy of nature, we may proceed to describe their subdivisions and form. For practical convenience rather than academic accuracy, we may accept the simple division of the family of bacteria into three chief forms, viz.:-- { (1) Round cell form--_coccus_. { Lower Bacteria { (2) Rod form--_bacillus_. { { (3) Thread form--_spirillum_. Higher Bacteria--Leptothrix, Streptothrix, Cladothrix, etc. A classification dependent as this is upon the form alone is not by any means ideal, for it ignores all the higher and complicated functions of bacteria, but it is, as we have said, practically convenient. [Illustration: VARIOUS FORMS OF BACTERIA 1. Micrococcus 2. Diplococcus 3. Streptococcus 4. Staphylococcus 5. Leuconostoc, showing Arthrospores 6. Merismopedia 7. Sarcina 8. Bacilli 9. Spirillum]