PLATE XIIL— BACTEEIA, or SCHIZOMYCETES. 



(Gr. schisis, a splitting.) 

 (Fig. 8 is after Ewart, the rest after Dodel-Port, based on Dr. Kocfi's photographs.) 



Bacteria are those organisms which produce the change in organic bodies known 

 as Putrefaction. Hay Bacteria, developed in an infusion of hay, may be profitably 

 examined first. Take some fresh hay, pour hot water upon it, and allow to stand. 

 In the course of a day or two the liquid becomes turbid, due to the presence of 

 Bacteria, and latterly it has the smeU of decaying organic matter. If a drop of 

 this liquid be examined under the highest power of the microscope, it will be found 

 to contain Bacteria of simple form. 



Figures X 3000, except Fig. 8. 

 Fig. 1. Micrococci (Gr. mikros, little ; JcoJcJcos, a berry) are simply small, round, 

 or oval cells, occurring free, or in chain-Uke rows, or imited into a 

 gelatinous mass. They are remarkable for the bright coloiu-ing 

 matters with which they are tinged — red, blue, &c. 



Micrococcus prodigiosus — the blood-red Micrococcus — is a 

 spherical form, appearing as blood-red, slimy drops on stale 

 potatoes, bread, damp wafers, and the like. From its sudden ap- 

 pearance (often arising in the course of a single night) it has often 

 been superstitiously regarded as an evil omen, as stories of " bleeding 

 bread " or " bleeding wafers " testify. The colouring matter is 

 insoluble in water, but may be extracted by alcohol or ether. 

 Fig. 2. A chain of Micrococci found in putrefying blood. 



This chain has probably originated from the repeated division 

 of a single individual. The single cell lengthens as it grows, then 

 forms a sort of figure of 8 preliminary to division, and this repeated 

 again and again would give rise to the chain. 

 Fig. 3. A gelatinous film or Zoogloea. 



This film or scum forms on the surface of putrefying fluids, 

 and consists of a nimiber of Micrococci embedded in rows in a gela- 

 tinous material This arrangement in rows has probably been pro- 

 duced, as in Fig. 2, by repeated division, as some are found in that 

 condition. 

 Fig. 4. Bacteria (Gr. baJcterion, a staff), or Cylindrical Forms — the two red 

 blood-corpuscles are merely represented to show relative size. 



These forms are the first found in the body after death. Thej 

 are short or long rods, multiplying by transverse division. 

 Fig. 5. Rods from putrefying vegetable matter, with a vibratile cilium at 



each end, by means of which they wriggle about 

 Fig. 6. Sjyirochcete (Gr. chaite, haii-), or Relapsing Fever Bacteria, occurring 

 in the blood of fever patients. 



The spiral fUaments are flexible and exhibit wave-like move- 

 ments, which is often revealed by the motion imparted to the blood- 

 corpuscles in the neighbourhood. 

 Fig. 7. Spirillum — to be found in puddles in summer where there is decaying 

 vegetable matter. 



They form inflexible spiral filaments, of one or several turns, 

 and have a vibratile cUium at each end. 

 Fig. 8. Development of Spirillum — a to i. 



(a.) Zoogloea-stage — motionless forms embedded in gelatinous 



material. 

 (b. ) Vibrio-stage — bow-shaped forms passing into spiral forms, 

 (c.) Filamentous-stage — the last elongated. 

 {d.) Filamentous-stage — further developed forms, in which the 



filament is long and motionless, 

 (e. ) Filamentous-stage — Spore-producing filament. 

 (/.) Filamentous- stage — ripe and motile filament. 

 (g.) FUamentous-stage — fUament breaking up. 

 (h.) Spores which encyst and divide to form sporules. 

 ( t. ) Spores germinating — little comma-shaped bodies which repro 

 duce the original Spirillum. 



Life Hiitory Diagram. — The stages are here given through which SpirUhm 

 jjasatjs lu order to complete the cycle of its life. 



