THE SAPEOPHYTIC BACTERIA 109 



and the cilia which they bear beyond the average in length. In liquid 

 media long threads are formed and, if cultivated at 30°40° C, abundant 

 spore-formation is the result. As the spores are usually formed at the 

 ends of the rods, the latter have a characteristic drum-stick appear- 

 ance (Fig. 70). This species grows well anaerobically, both in media 

 containing and in those devoid 

 of sugar, usually developing an 

 abundance of gas. Gelatine cul- 

 tures of this species emit a very 

 foul smelling odour. 



Other anaerobic bacteria, which 

 are, however, less common, are 

 Bacillus perfringens, Bac. Kfermerir- ^"'- ™.-Bac. putnflous. spore-forming 

 tans sporogenes, and Bac. gracilis 



pwtidus. The first two are sporogenous, whilst the last named does 

 not form spores. They differ in the nature of the decompositions that 

 they set up and in some of their morphological characteristics. 



The Principal Changes that take place in Decomposition. The decom- 

 position of organic matter does not necessarily always follow along the 

 same lines. The particular course that will be followed depends on 

 the nature of the material, on the amount of sugar that the material 

 contains, on the temperature, on the oxygen supply, on the bacteria 

 that are present, and on several other factors. In fact, it very seldom 

 happens that the details of decomposition are alike in any two 

 particular cases. Yet, in spite of differences of detail, the general 

 trend is very much the same in all, and this trend we now propose 

 to follow. From the bacteriological point of view we may consider 

 all organic remains as consisting of proteids,^ sugars, and fats in varied 

 proportions. 



' Proteids or albmninoids are complicated substances that occur in animal and 

 in vegetable tissues. Their chemical oonstitxition has not yet been discovered. 

 They contain 54 parts of carbon, 7 of hydrogen, 16 of nitrogen, 21 of oxygen, 

 and 1-1 J of sulphur. They are divided into the following classes : 



1. Albumins, soluble in water. Ex. Egg-cdhumen. 



2. Globulins, insohible in water, soluble in dilute acids and alkalies, soluble in 



1 per cent, common salt solution. Exs. Olohidin, myosin. 



3. Derived albumins, insoluble in water and common salt solution, soluble in 



dilute acids and alkalies. Ex. Casein. 



4. Fibrin, insoluble in water, sparingly soluble in dilute acids and alkalies and 



in neutral saline solutions. Exs. Fibrin and gluten. 



5. Coagulated proteids, soluble in gastric juice. Ex. Coagvlated albumin. 



6. Amyloids, insoluble in gastric juice. 



