THE BIOLOGY OF BACTERIA 



Thallophyta. 



[ = The lowest forms 

 of vegetable life. No 

 differentiation into 

 root, stem, or leaf.] 



VEGETABLE KINGDOM. 



I 



i i I 



Muscineae. Pteridophyta. Phanerogamia. 



I 



Algae. 



[=Chlorophyll 



present.] 



Fungi. 



[ = No Chlorophyll.] 



Hymenomycetes. 



(Mushrooms, etc.) 



Hyphomycetes. 



(Moulds.) 



Blastomycetes. 



(Yeasts, etc.) 



Schizomycetes 



[= multiplication by cell 

 division or by spores] 

 or 

 Bacteria. 



(1) Coccaceas* — round 



cells. 



(2) Bacteriaceae — rods 



and threads. 



(3) Leptotricheas. 



(4) Cladotricheae. 





* Migula has suggested that the Schizomycetes should be subdivided into Coccacece, BmUnacsoi, SpirUlaceai 

 (spirilla, spirochcsta), Chlamydobacterimiece (Streptothrix, Crenothrix, Cladothrix), and Beggiatoa. 



Morphology: 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 theoretical accuracy, we may accept 

 the simple division of the family of bacteria into three chief forms, 

 viz. : — 



r (1) Eound cell form — coccus. 

 Lower Bacteria -| (2) Eod form — hacillus. 



\ (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 complicated functions of 

 bacteria, but it is, as we have said, practically convenient. 



1. The Coccus. — This is the group of round cells. They vary in 

 size as regards species, and as regards the conditions, artificial or 

 natural, under which they have been grown. Some are less than 

 ushm of a-n inch in diameter ; others are half as large again, if the 

 word large may be used to describe such minute objects. No regular 

 standard can be laid down as reliable with regard to their size. 

 Hence the subdivisions of the cocci are dependent not upon the 

 individual elements so much as upon the relation of those elements to 

 each other. A simple round cell of approximately the size already 

 named is termed a micrococcus (fjuKpos, small). Certain species of 



