14 BACTERIOLOGY 



" pseudopodia." (In this group is to be found the organism 

 (Entamoeba histolytica) which causes Tropical or Amoebic 

 Dysentery in man. 



2. Flagellata or Mastigophora : possessing one or two, 

 rarely a larger number of vibratile hair-like organs. (Members 

 of this class include the parasites of Sleeping Sickness in man, 

 and also certain very serious diseases of cattle, horses, and 

 other animals.) 



3. Ciliata : possessing numerous short, vibratile, hair-like 

 " cilia " for locomotion and for waving food-particles into the 

 mouth. (The members of this group are not of any great im- 

 portance from our present point of view.) 



4. Suctoria or Acinetaria : none of these is known to pro- 

 duce disease in man. 



5. Sporozoa : members of this class are all parasitic. They 

 feed by absorption, and, except during certain developmental 

 stages, do not possess specialised organs for locomotion. 

 (Malaria, one of the most widespread and serious diseases 

 affecting mankind, is produced by certain closely allied members 

 of this group, whilst others infest and produce important dis- 

 eases in many of the lower animals.) 



From a study of the above facts we are now in a position to 

 realise in some degree what we mean by the terms bacteria, 

 microbe, and the like. We see that, as we pass down the animal 

 and vegetable series, the two main lines approach each other 

 like the limbs of a gigantic letter V, and very near practically 

 at the point of junction come the "Protozoa "or primitive 

 animals and the " Protophyta," as we may correspondingly name 

 the primitive plants. 



Many of the bacteria resemble animals in being capable of 

 active movement, but it is, of course, common knowledge that 

 this is no real test, for many true animals, sea-anemones, 

 sponges, and the like, are stationary ; whilst some plants and 

 vegetable cells can actively move from place to place. The 

 more important tests are physiological, i.e. connected with the 

 vital activities such as food-absorption, excretion of waste pro- 

 ducts, and so on, and, though of great scientific interest, 

 scarcely come within the scope of the present volume. 



The Classification of the Fission-Fungi (Schizomycetes) 



or Bacteria into Families 



As this is a matter of great difficulty and complexity, only 

 a short outline need be here attempted. Indeed it is no ex- 

 aggeration to say that one finds a different classification given 

 in almost every book dealing with bacteriology. This is mainly 



